[hexagon] Define __ELF__ by default.

[sidneym]

Summary

ELF is not enabled by default. Correcting an issue in compiler-rt's cmake revealed that ELF was not defined.

clang/lib/Basic/Targets/Hexagon.cpp

 using namespace clang;
 using namespace clang::targets;
 
 void HexagonTargetInfo::getTargetDefines(const LangOptions &Opts,
                                          MacroBuilder &Builder) const {
   Builder.defineMacro("__qdsp6__", "1");
   Builder.defineMacro("__hexagon__", "1");
 
+  Builder.defineMacro("__ELF__");
+
   // The macro __HVXDBL__ is deprecated.
   bool DefineHvxDbl = false;
 
   if (CPU == "hexagonv5") {
     Builder.defineMacro("__HEXAGON_V5__");
     Builder.defineMacro("__HEXAGON_ARCH__", "5");
     if (Opts.HexagonQdsp6Compat) {
       Builder.defineMacro("__QDSP6_V5__");

clang/test/Preprocessor/hexagon-predefines.c

 // RUN: -target-feature +hvxv67 -target-feature +hvx-length128b %s | FileCheck \
 // RUN: %s -check-prefix CHECK-V67HVX-128B
 // CHECK-V67HVX-128B: #define __HEXAGON_ARCH__ 67
 // CHECK-V67HVX-128B: #define __HEXAGON_V67__ 1
 // CHECK-V67HVX-128B: #define __HVX_ARCH__ 67
 // CHECK-V67HVX-128B: #define __HVX_LENGTH__ 128
 // CHECK-V67HVX-128B: #define __HVX__ 1
 // CHECK-V67HVX-128B: #define __hexagon__ 1
+
+// RUN: %clang_cc1 -E -dM -triple hexagon-unknown-elf -target-cpu hexagonv67 \
+// RUN: -target-feature +hvxv67 -target-feature +hvx-length128b %s | FileCheck \
+// RUN: %s -check-prefix CHECK-ELF
+// CHECK-ELF: #define __ELF__ 1

compiler-rt/lib/builtins/CMakeLists.txt

 set(arm64_SOURCES ${aarch64_SOURCES})
 
 # macho_embedded archs
 set(armv6m_SOURCES ${thumb1_SOURCES})
 set(armv7m_SOURCES ${arm_SOURCES})
 set(armv7em_SOURCES ${arm_SOURCES})
 
 # hexagon arch
-set(hexagon_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
 set(hexagon_SOURCES
   hexagon/common_entry_exit_abi1.S
   hexagon/common_entry_exit_abi2.S
   hexagon/common_entry_exit_legacy.S
   hexagon/dfaddsub.S
   hexagon/dfdiv.S
   hexagon/dffma.S
   hexagon/dfminmax.S
set(hexagon_SOURCES
   hexagon/sfdiv_opt.S
   hexagon/sfsqrt_opt.S
   hexagon/udivdi3.S
   hexagon/udivmoddi4.S
   hexagon/udivmodsi4.S
   hexagon/udivsi3.S
   hexagon/umoddi3.S
   hexagon/umodsi3.S
+  ${GENERIC_SOURCES}
+  ${GENERIC_TF_SOURCES}
 )
 
 
 set(mips_SOURCES ${GENERIC_SOURCES})
 set(mipsel_SOURCES ${mips_SOURCES})
 set(mips64_SOURCES ${GENERIC_TF_SOURCES}
                    ${mips_SOURCES})
 set(mips64el_SOURCES ${GENERIC_TF_SOURCES}