Stop passing -fomit-frame-pointers in swiftshader build file

The //build/config files have a whole song and dance about
frame pointers in //build/config/compiler:default_stack_frames
and //build/config/compiler/compiler.gni (enable_frame_pointers),
so rely on that.

This has the effect of enabling frame pointers in more configs,
which happens to work around an lld/mac bug -- but this seems
like a good change regardless.

Bug: chromium:1220175
Change-Id: I59dbb80fce2c50db658c3cf0cb13690ced88cbfe
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/55630
Tested-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Commit-Queue: Nico Weber <thakis@chromium.org>
diff --git a/BUILD.gn b/BUILD.gn
index 47753c7..fd2cf7f 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -53,10 +53,7 @@
         [ "NO_SANITIZE_FUNCTION=__attribute__((no_sanitize(\"function\")))" ]
 
     if (!is_debug) {
-      cflags += [
-        "-fomit-frame-pointer",
-        "-Os",
-      ]
+      cflags += [ "-Os" ]
 
       defines += [ "ANGLE_DISABLE_TRACE" ]
     }