Fix breakage in D89615 (due to cmake version 3.16.5)

[fhahn]

LGTM, things build again with cmake 3.16.5. Can't say anything beyond that, so it might be good for others to also take a look.

[oontvoo]

updated

[oontvoo]

In D90764#2373722, @fhahn wrote:

LGTM, things build again with cmake 3.16.5. Can't say anything beyond that, so it might be good for others to also take a look.

Thanks!
We've tested the rest of the previous patch. They also weren't cmake-specific, so I think it should be fine.

compiler-rt/CMakeLists.txt

 
 construct_compiler_rt_default_triple()
 if ("${COMPILER_RT_DEFAULT_TARGET_TRIPLE}" MATCHES ".*hf$")
   if (${COMPILER_RT_DEFAULT_TARGET_ARCH} MATCHES "^arm")
     set(COMPILER_RT_DEFAULT_TARGET_ARCH "armhf")
     CHECK_SYMBOL_EXISTS (__thumb__ "" COMPILER_RT_ARM_THUMB)
   endif()
 endif()
+
+set(ANDROID_HAS_ELF_TLS 0)
 if ("${COMPILER_RT_DEFAULT_TARGET_TRIPLE}" MATCHES ".*android.*")
   set(ANDROID 1)
+  CHECK_CXX_SOURCE_COMPILES("
+int main() {
+#if __ANDROID_API__ >= 28
+    return 0;
+#else
+  #error NO_ELF_TLS
+  return 1;
+#endif
+}
+  " ANDROID_HAS_ELF_TLS)
   string(REGEX MATCH "-target(=| +)[^ ]+android([0-9]+)" ANDROID_API_LEVEL "${CMAKE_C_FLAGS}")
   set(ANDROID_API_LEVEL ${CMAKE_MATCH_2}) 
 endif()
 pythonize_bool(ANDROID)
 
 set(COMPILER_RT_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 set(COMPILER_RT_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
 

 append_string_if(COMPILER_RT_HAS_STD_CXX14_FLAG -std=c++14 CMAKE_CXX_FLAGS)
 
 # Emulate C99 and C++11's __func__ for MSVC prior to 2013 CTP.
 if(NOT COMPILER_RT_HAS_FUNC_SYMBOL)
   add_definitions(-D__func__=__FUNCTION__)
 endif()
 
 # Provide some common commmandline flags for Sanitizer runtimes.
-if(${ANDROID_API_LEVEL} GREATER_EQUAL 28)
+if(ANDROID_HAS_ELF_TLS)
   list(APPEND SANITIZER_COMMON_CFLAGS -fno-emulated-tls)
   list(APPEND COMPILER_RT_TEST_COMPILER_CFLAGS -fno-emulated-tls)
 endif()
 if(NOT WIN32)
   append_list_if(COMPILER_RT_HAS_FPIC_FLAG -fPIC SANITIZER_COMMON_CFLAGS)
 endif()
 append_list_if(COMPILER_RT_HAS_FNO_BUILTIN_FLAG -fno-builtin SANITIZER_COMMON_CFLAGS)
 append_list_if(COMPILER_RT_HAS_FNO_EXCEPTIONS_FLAG -fno-exceptions SANITIZER_COMMON_CFLAGS)