[Clang] Force rtlib=platform in test to avoid fails with CLANG_DEFAULT_RTLIB

[kristina]

Summary

Driver test cross-linux.c fails when CLANG_DEFAULT_RTLIB is "compiler-rt"
as the it expects a GCC-style "crtbegin.o" after "crti.o" but instead
receives something akin to this in the frontend invocation:

"crt1.o" "crti.o" "/o/b/llvm-test/v10.0.4010/bin/../lib/clang/10.0.4010/lib/linux/clang_rt.crtbegin-x86_64.o"

In lib/Driver/ToolChain.cpp it's implied that using --rtlib=platform is
acceptable in tests to override the configuration-time default.

// Only use "platform" in tests to override CLANG_DEFAULT_RTLIB
// ...
else if (LibName == "platform")
  return GetDefaultRuntimeLibType();

This patch adds said override to cross-linux.c tests so the expected result
is produced regardless of the compile-time default rtlib, as having tests
fail due to that is fairly confusing. After applying the patch, the test passes
regardless of the CLANG_DEFAULT_RTLIB setting.

nb. Originally ran across this issue in D69758.

[merge_guards_bot]

Unit tests: pass. 61250 tests passed, 0 failed and 736 were skipped.

clang-tidy: fail. Please fix clang-tidy findings.

clang-format: fail. Please format your changes with clang-format by running git-clang-format HEAD^ or applying this patch.

Build artifacts: diff.json, clang-tidy.txt, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

[MaskRay]

LGTM

clang/test/Driver/cross-linux.c

 // CHECK-MULTI32-I386: "-L[[gcc_install]]/../../../../i386-unknown-linux/lib/../lib32"
 // CHECK-MULTI32-I386: "-L[[gcc_install]]/../../../../i386-unknown-linux/lib"
 // CHECK-MULTI32-I386: "-L[[sysroot]]/lib"
 // CHECK-MULTI32-I386: "-L[[sysroot]]/usr/lib"
 //
 // RUN: %clang -### -o %t %s 2>&1 -no-integrated-as -fuse-ld=ld \
 // RUN:   --gcc-toolchain=%S/Inputs/multilib_32bit_linux_tree/usr \
 // RUN:   --target=x86_64-unknown-linux \
+// RUN:   --rtlib=platform \
 // RUN:   --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-MULTI32-X86-64 %s
 // CHECK-MULTI32-X86-64: "-cc1" "-triple" "x86_64-unknown-linux"
 // CHECK-MULTI32-X86-64: "{{.*}}/Inputs/multilib_32bit_linux_tree/usr/lib/gcc/i386-unknown-linux/4.6.0/../../../../i386-unknown-linux/bin{{/|\\\\}}as" "--64"
 // CHECK-MULTI32-X86-64: "{{.*}}/Inputs/multilib_32bit_linux_tree/usr/lib/gcc/i386-unknown-linux/4.6.0/../../../../i386-unknown-linux/bin{{/|\\\\}}ld"
 // CHECK-MULTI32-X86-64: "--sysroot=[[sysroot:.*/Inputs/basic_linux_tree]]"
 // CHECK-MULTI32-X86-64: "-m" "elf_x86_64"
 // CHECK-MULTI32-X86-64: "crti.o" "[[gcc_install:.*/Inputs/multilib_32bit_linux_tree/usr/lib/gcc/i386-unknown-linux/4.6.0]]/64{{/|\\\\}}crtbegin.o"
 // CHECK-MULTI32-X86-64: "-L[[gcc_install]]/64"
 // CHECK-MULTI32-X86-64: "-L[[gcc_install]]/../../../../i386-unknown-linux/lib/../lib64"
 // CHECK-MULTI32-X86-64: "-L[[gcc_install]]"
 // CHECK-MULTI32-X86-64: "-L[[gcc_install]]/../../../../i386-unknown-linux/lib"
 // CHECK-MULTI32-X86-64: "-L[[sysroot]]/lib"
 // CHECK-MULTI32-X86-64: "-L[[sysroot]]/usr/lib"
 //
 // RUN: %clang -### -o %t %s 2>&1 -no-integrated-as -fuse-ld=ld \
 // RUN:   --gcc-toolchain=%S/Inputs/multilib_64bit_linux_tree/usr \
 // RUN:   --target=i386-unknown-linux \
+// RUN:   --rtlib=platform \
 // RUN:   --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-MULTI64-I386 %s
 // CHECK-MULTI64-I386: "-cc1" "-triple" "i386-unknown-linux"
 // CHECK-MULTI64-I386: "{{.*}}/Inputs/multilib_64bit_linux_tree/usr/lib/gcc/x86_64-unknown-linux/4.6.0/../../../../x86_64-unknown-linux/bin{{/|\\\\}}as" "--32"
 // CHECK-MULTI64-I386: "{{.*}}/Inputs/multilib_64bit_linux_tree/usr/lib/gcc/x86_64-unknown-linux/4.6.0/../../../../x86_64-unknown-linux/bin{{/|\\\\}}ld"
 // CHECK-MULTI64-I386: "--sysroot=[[sysroot:.*/Inputs/basic_linux_tree]]"
 // CHECK-MULTI64-I386: "-m" "elf_i386"
 // CHECK-MULTI64-I386: "crti.o" "[[gcc_install:.*/Inputs/multilib_64bit_linux_tree/usr/lib/gcc/x86_64-unknown-linux/4.6.0]]/32{{/|\\\\}}crtbegin.o"
 // CHECK-MULTI64-I386: "-L[[gcc_install]]/32"
 // CHECK-MULTI64-I386: "-L[[gcc_install]]/../../../../x86_64-unknown-linux/lib/../lib32"
 // CHECK-MULTI64-I386: "-L[[gcc_install]]"
 // CHECK-MULTI64-I386: "-L[[gcc_install]]/../../../../x86_64-unknown-linux/lib"
 // CHECK-MULTI64-I386: "-L[[sysroot]]/lib"
 // CHECK-MULTI64-I386: "-L[[sysroot]]/usr/lib"
 //
 // RUN: %clang -### -o %t %s 2>&1 -no-integrated-as -fuse-ld=ld \
 // RUN:   --gcc-toolchain=%S/Inputs/multilib_64bit_linux_tree/usr \
 // RUN:   --target=x86_64-unknown-linux \
+// RUN:   --rtlib=platform \
 // RUN:   --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-MULTI64-X86-64 %s
 // CHECK-MULTI64-X86-64: "-cc1" "-triple" "x86_64-unknown-linux"
 // CHECK-MULTI64-X86-64: "{{.*}}/Inputs/multilib_64bit_linux_tree/usr/lib/gcc/x86_64-unknown-linux/4.6.0/../../../../x86_64-unknown-linux/bin{{/|\\\\}}as" "--64"
 // CHECK-MULTI64-X86-64: "{{.*}}/Inputs/multilib_64bit_linux_tree/usr/lib/gcc/x86_64-unknown-linux/4.6.0/../../../../x86_64-unknown-linux/bin{{/|\\\\}}ld"
 // CHECK-MULTI64-X86-64: "--sysroot=[[sysroot:.*/Inputs/basic_linux_tree]]"
 // CHECK-MULTI64-X86-64: "-m" "elf_x86_64"
 // CHECK-MULTI64-X86-64: "crti.o" "[[gcc_install:.*/Inputs/multilib_64bit_linux_tree/usr/lib/gcc/x86_64-unknown-linux/4.6.0]]{{/|\\\\}}crtbegin.o"
 // CHECK-MULTI64-X86-64: "-L[[gcc_install]]"
 // CHECK-MULTI64-X86-64: "-L[[gcc_install]]/../../../../x86_64-unknown-linux/lib/../lib64"
 // CHECK-MULTI64-X86-64: "-L[[gcc_install]]/../../../../x86_64-unknown-linux/lib"
 // CHECK-MULTI64-X86-64: "-L[[sysroot]]/lib"
 // CHECK-MULTI64-X86-64: "-L[[sysroot]]/usr/lib"