[cmake] Work around -Wunused-driver-argument warnings

Fix the Darwin logic so that -msse3 is only used on macOS, and
-fomit-frame-pointer is not used on armv7/armv7k/armv7s.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@312390 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/cmake/Modules/CompilerRTDarwinUtils.cmake b/cmake/Modules/CompilerRTDarwinUtils.cmake
index 7fdb111..a25540b 100644
--- a/cmake/Modules/CompilerRTDarwinUtils.cmake
+++ b/cmake/Modules/CompilerRTDarwinUtils.cmake
@@ -200,10 +200,23 @@
   if(DARWIN_${LIB_OS}_SYSROOT)
     set(sysroot_flag -isysroot ${DARWIN_${LIB_OS}_SYSROOT})
   endif()
+
+  # Make a copy of the compilation flags.
+  set(builtin_cflags ${LIB_CFLAGS})
+
+  # Strip out any inappropriate flags for the target.
+  if("${LIB_ARCH}" MATCHES "^(armv7|armv7k|armv7s)$")
+    set(builtin_cflags "")
+    foreach(cflag "${LIB_CFLAGS}")
+      string(REPLACE "-fomit-frame-pointer" "" cflag "${cflag}")
+      list(APPEND builtin_cflags ${cflag})
+    endforeach(cflag)
+  endif()
+
   set_target_compile_flags(${libname}
     ${sysroot_flag}
     ${DARWIN_${LIB_OS}_BUILTIN_MIN_VER_FLAG}
-    ${LIB_CFLAGS})
+    ${builtin_cflags})
   set_property(TARGET ${libname} APPEND PROPERTY
       COMPILE_DEFINITIONS ${LIB_DEFS})
   set_target_properties(${libname} PROPERTIES