Fix the cross compilation of unit tests. NFC (second attempt)

[sgundapa]

Summary

With COMPILER_RT_INCLUDE_TESTS turned ON and in a cross compiling
environment, the unit tests fail to link. This patch does the following changes

Rename COMPILER_RT_TEST_CFLAGS to COMPILER_RT_UNITTEST_CFLAGS to reflect the way it's used.
Add COMPILER_RT_TEST_COMPILER_CFLAGS to COMPILER_RT_UNITTEST_CFLAGS so that cross-compiler would be able to build/compile the unit tests
Add COMPILER_RT_UNITTEST_LINKFLAGS to COMPILER_RT_UNITTEST_CFLAGS so that cross-compiler would be able to link the unit tests (if needed)

[samsonov]

LGTM

cmake/Modules/AddCompilerRT.cmake

if(type STREQUAL "SHARED")
       rt_externalize_debuginfo(${libname})
     endif()
   endforeach()
   if(LIB_PARENT_TARGET)
     add_dependencies(${LIB_PARENT_TARGET} ${libnames})
   endif()
 endfunction()
 
-set(COMPILER_RT_TEST_CFLAGS)
+# when cross compiling, COMPILER_RT_TEST_COMPILER_CFLAGS help
+# in compilation and linking of unittests.
+string(REPLACE " " ";" COMPILER_RT_UNITTEST_CFLAGS "${COMPILER_RT_TEST_COMPILER_CFLAGS}")
+set(COMPILER_RT_UNITTEST_LINKFLAGS ${COMPILER_RT_UNITTEST_CFLAGS})
 
 # Unittests support.
 set(COMPILER_RT_GTEST_PATH ${LLVM_MAIN_SRC_DIR}/utils/unittest/googletest)
 set(COMPILER_RT_GTEST_SOURCE ${COMPILER_RT_GTEST_PATH}/src/gtest-all.cc)
 set(COMPILER_RT_GTEST_CFLAGS
   -DGTEST_NO_LLVM_RAW_OSTREAM=1
   -DGTEST_HAS_RTTI=0
   -I${COMPILER_RT_GTEST_PATH}/include
   -I${COMPILER_RT_GTEST_PATH}
 )
 
-append_list_if(COMPILER_RT_DEBUG -DSANITIZER_DEBUG=1 COMPILER_RT_TEST_CFLAGS)
+append_list_if(COMPILER_RT_DEBUG -DSANITIZER_DEBUG=1 COMPILER_RT_UNITTEST_CFLAGS)
 
 if(MSVC)
   # clang doesn't support exceptions on Windows yet.
-  list(APPEND COMPILER_RT_TEST_CFLAGS -D_HAS_EXCEPTIONS=0)
+  list(APPEND COMPILER_RT_UNITTEST_CFLAGS -D_HAS_EXCEPTIONS=0)
 
   # We should teach clang to understand "#pragma intrinsic", see PR19898.
-  list(APPEND COMPILER_RT_TEST_CFLAGS -Wno-undefined-inline)
+  list(APPEND COMPILER_RT_UNITTEST_CFLAGS -Wno-undefined-inline)
 
   # Clang doesn't support SEH on Windows yet.
   list(APPEND COMPILER_RT_GTEST_CFLAGS -DGTEST_HAS_SEH=0)
 
   # gtest use a lot of stuff marked as deprecated on Windows.
   list(APPEND COMPILER_RT_GTEST_CFLAGS -Wno-deprecated-declarations)
 
   # Visual Studio 2012 only supports up to 8 template parameters in

lib/asan/tests/CMakeLists.txt

 include_directories(../..)
 
 set(ASAN_UNITTEST_HEADERS
   asan_mac_test.h
   asan_test_config.h
   asan_test_utils.h)
 
 set(ASAN_UNITTEST_COMMON_CFLAGS
-  ${COMPILER_RT_TEST_CFLAGS}
+  ${COMPILER_RT_UNITTEST_CFLAGS}
   ${COMPILER_RT_GTEST_CFLAGS}
   -I${COMPILER_RT_SOURCE_DIR}/include
   -I${COMPILER_RT_SOURCE_DIR}/lib
   -I${COMPILER_RT_SOURCE_DIR}/lib/asan
   -I${COMPILER_RT_SOURCE_DIR}/lib/sanitizer_common/tests
   -fno-rtti
   -O2
   -Wno-format
   -Werror=sign-compare
   -Wno-non-virtual-dtor)
 append_list_if(COMPILER_RT_HAS_WVARIADIC_MACROS_FLAG -Wno-variadic-macros ASAN_UNITTEST_COMMON_CFLAGS)
 
+# This will ensure the target linker is used
+# during cross compilation
+set(ASAN_UNITTEST_COMMON_LINKFLAGS
+  ${COMPILER_RT_UNITTEST_LINKFLAGS})
+
 # -gline-tables-only must be enough for ASan, so use it if possible.
 if(COMPILER_RT_TEST_COMPILER_ID MATCHES "Clang")
   list(APPEND ASAN_UNITTEST_COMMON_CFLAGS -gline-tables-only)
 else()
   list(APPEND ASAN_UNITTEST_COMMON_CFLAGS -g)
 endif()
 
 # Use -D instead of definitions to please custom compile command.

lib/msan/tests/CMakeLists.txt

 set(MSAN_LOADABLE_SOURCE msan_loadable.cc)
 set(MSAN_UNITTEST_HEADERS
   msan_test_config.h
   ../../../include/sanitizer/msan_interface.h
 )
 set(MSAN_UNITTEST_COMMON_CFLAGS
   -nostdinc++
   -isystem ${COMPILER_RT_LIBCXX_PATH}/include
-  ${COMPILER_RT_TEST_CFLAGS}
+  ${COMPILER_RT_UNITTEST_CFLAGS}
   ${COMPILER_RT_GTEST_CFLAGS}
   -I${COMPILER_RT_SOURCE_DIR}/include
   -I${COMPILER_RT_SOURCE_DIR}/lib
   -I${COMPILER_RT_SOURCE_DIR}/lib/msan
   -g
   -O2
   -fno-exceptions
   -fno-omit-frame-pointer

lib/sanitizer_common/tests/CMakeLists.txt

set(SANITIZER_TEST_HEADERS
   sanitizer_pthread_wrappers.h
   sanitizer_test_config.h
   sanitizer_test_utils.h)
 foreach(header ${SANITIZER_HEADERS})
   list(APPEND SANITIZER_TEST_HEADERS ${CMAKE_CURRENT_SOURCE_DIR}/../${header})
 endforeach()
 
 set(SANITIZER_TEST_CFLAGS_COMMON
-  ${COMPILER_RT_TEST_CFLAGS}
+  ${COMPILER_RT_UNITTEST_CFLAGS}
   ${COMPILER_RT_GTEST_CFLAGS}
   -I${COMPILER_RT_SOURCE_DIR}/include
   -I${COMPILER_RT_SOURCE_DIR}/lib
   -I${COMPILER_RT_SOURCE_DIR}/lib/sanitizer_common
   -fno-rtti
   -O2
   -Werror=sign-compare
   -Wno-non-virtual-dtor)

lib/tsan/tests/CMakeLists.txt

 include_directories(../rtl)
 
 add_custom_target(TsanUnitTests)
 set_target_properties(TsanUnitTests PROPERTIES
   FOLDER "TSan unittests")
 
 set(TSAN_UNITTEST_CFLAGS
   ${TSAN_CFLAGS}
-  ${COMPILER_RT_TEST_CFLAGS}
+  ${COMPILER_RT_UNITTEST_CFLAGS}
   ${COMPILER_RT_GTEST_CFLAGS}
   -I${COMPILER_RT_SOURCE_DIR}/lib
   -I${COMPILER_RT_SOURCE_DIR}/lib/tsan/rtl
   -DGTEST_HAS_RTTI=0)
 
 set(TSAN_RTL_HEADERS)
 foreach (header ${TSAN_HEADERS})
   list(APPEND TSAN_RTL_HEADERS ${CMAKE_CURRENT_SOURCE_DIR}/../${header})