[compiler-rt] Fix target architecture matching

[fjricci]

Summary

Use stricter comparisons for architecture. This prevents cmake from failing
for sysroots which can only compile armhf and not arm, since
arm MATCHES armhf is true, while arm STREQUAL armhf is false.

[compnerd]

Doesn't this break down where previously this would support matching arm with armv7?

[fjricci]

Yes. So in that case, it will still fail to find and build for the armv7 arch, as before, the cmake run will just not fail. Given that this check is for when the architecture is explicitly specified by the user, if one wanted to ensure matching with arm, they could provide arm instead of armv7 on the cmake command line.

compiler-rt/trunk/cmake/Modules/CompilerRTUtils.cmake

else()
     set(argstring "${CMAKE_EXE_LINKER_FLAGS} ${argstring}")
     try_compile(CAN_TARGET_${arch} ${CMAKE_BINARY_DIR} ${SIMPLE_SOURCE}
                 COMPILE_DEFINITIONS "${TARGET_${arch}_CFLAGS}"
                 OUTPUT_VARIABLE TARGET_${arch}_OUTPUT
                 CMAKE_FLAGS "-DCMAKE_EXE_LINKER_FLAGS:STRING=${argstring}")
   endif()
   if(${CAN_TARGET_${arch}})
     list(APPEND COMPILER_RT_SUPPORTED_ARCH ${arch})
-  elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "${arch}" AND
+  elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" STREQUAL "${arch}" AND
          COMPILER_RT_HAS_EXPLICIT_DEFAULT_TARGET_TRIPLE)
     # Bail out if we cannot target the architecture we plan to test.
     message(FATAL_ERROR "Cannot compile for ${arch}:\n${TARGET_${arch}_OUTPUT}")
   endif()
 endmacro()
 
 macro(detect_target_arch)
   check_symbol_exists(__arm__ "" __ARM)