PR review comments

Author: vinay-deshmukh

libc/cmake/modules/LLVMLibCTestRules.cmake

@@ -34,6 +34,7 @@ function(_get_common_test_compile_options output_var c_test flags)
     # list(APPEND compile_options "-Wconversion")
     # list(APPEND compile_options "-Wno-sign-conversion")
     list(APPEND compile_options "-Wimplicit-fallthrough")
+    list(APPEND compile_options "-Wstrict-prototypes")
     list(APPEND compile_options "-Wwrite-strings")
     list(APPEND compile_options "-Wextra-semi")
     # Silence this warning because _Complex is a part of C99.
@@ -46,10 +47,9 @@ function(_get_common_test_compile_options output_var c_test flags)
       list(APPEND compile_options "-Wno-gnu-imaginary-constant")
     endif()
     list(APPEND compile_options "-Wno-pedantic")
-    if(NOT CMAKE_COMPILER_IS_GNUCXX)
+    if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
       list(APPEND compile_options "-Wnewline-eof")
       list(APPEND compile_options "-Wnonportable-system-include-path")
-      list(APPEND compile_options "-Wstrict-prototypes")
       list(APPEND compile_options "-Wthread-safety")
       # list(APPEND compile_options "-Wglobal-constructors")
     endif()