[HWASan] Remove -Wa,-mrelax-relocations=no flag.

[morehouse]

Summary

We no longer need it after https://reviews.llvm.org/D113220.

[morehouse]

• Fix FileCheck args.

[morehouse]

Ping. Parent patch landed last week.

compiler-rt/test/hwasan/TestCases/global.c

 // RUN: %clang_hwasan %s -o %t
 // RUN: %run %t 0
 // RUN: not %run %t 1 2>&1 | FileCheck --check-prefixes=CHECK,RSYM %s
 // RUN: not %env_hwasan_opts=symbolize=0 %run %t 1 2>&1 | FileCheck --check-prefixes=CHECK,RNOSYM %s
 // RUN: not %run %t -1 2>&1 | FileCheck --check-prefixes=CHECK,LSYM %s
 // RUN: not %env_hwasan_opts=symbolize=0 %run %t -1 2>&1 | FileCheck --check-prefixes=CHECK,LNOSYM %s
 
+// Test with LTO, since it invokes the integrated assembler separately.
+// RUN: %clang_hwasan -flto %s -o %t
+// RUN: not %run %t 1 2>&1 | FileCheck --check-prefixes=CHECK,RSYM %s
+
 // Test with and without optimizations, with and without PIC, since different
 // backend passes run depending on these flags.
 // RUN: %clang_hwasan -fno-pic %s -o %t
 // RUN: not %run %t 1 2>&1 | FileCheck --check-prefixes=CHECK,RSYM %s
 // RUN: %clang_hwasan -fno-pic -O2 %s -o %t
 // RUN: not %run %t 1 2>&1 | FileCheck --check-prefixes=CHECK,RSYM %s
 // RUN: %clang_hwasan -O2 %s -o %t
 // RUN: not %run %t 1 2>&1 | FileCheck --check-prefixes=CHECK,RSYM %s

compiler-rt/test/hwasan/lit.cfg.py

 clang_cxxflags = config.cxx_mode_flags + clang_cflags
 clang_hwasan_common_cflags = clang_cflags + ["-fsanitize=hwaddress", "-fuse-ld=lld"]
 
 if config.target_arch == 'x86_64' and config.enable_aliases == '1':
   clang_hwasan_common_cflags += ["-fsanitize-hwaddress-experimental-aliasing"]
 else:
   config.available_features.add('pointer-tagging')
 if config.target_arch == 'x86_64':
-  # By default the assembler uses R_X86_64_REX_GOTPCRELX relocations, which can
-  # be relaxed to direct references.  When tagged globals are enabled, these
-  # references fail to link since they have more than a 32-bit offset from RIP.
-  # As a workaround, we disable the relaxation.
-  # TODO: Implement a way to disable for the affected relocations only.
-  clang_hwasan_common_cflags += ["-Wa,-mrelax-relocations=no"]
-
   # The callback instrumentation used on x86_64 has a 1/64 chance of choosing a
   # stack tag of 0.  This causes stack tests to become flaky, so we force tags
   # to be generated via calls to __hwasan_generate_tag, which never returns 0.
   # TODO: See if we can remove this once we use the outlined instrumentation.
   clang_hwasan_common_cflags += ["-mllvm", "-hwasan-generate-tags-with-calls=1"]
 clang_hwasan_cflags = clang_hwasan_common_cflags + ["-mllvm", "-hwasan-globals",
                                                    "-mllvm", "-hwasan-use-short-granules",
                                                    "-mllvm", "-hwasan-instrument-landing-pads=0",