Fix breakage in D89615 (due to cmake version 3.16.5)

Differential Revision: https://reviews.llvm.org/D90764

Author: oontvoo

compiler-rt/CMakeLists.txt

@@ -119,8 +119,20 @@ if ("${COMPILER_RT_DEFAULT_TARGET_TRIPLE}" MATCHES ".*hf$")
     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()
@@ -277,7 +289,7 @@ if(NOT COMPILER_RT_HAS_FUNC_SYMBOL)
 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()