Stop -fdebug-info-for-profiling flag being applied to NaCl builds

The NaCl build doesn't seem to accept the the clang flag
-fdebug-info-profiling, so we need to make sure not to pass that
flag to NaCl builds when clang_emit_debug_info_for_profiling = true

Change-Id: Ib38f58c7a71939a9a8a124df5b6f2b798a93dab6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1890076Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: George Burgess <gbiv@chromium.org>
Reviewed-by: Johnny (Jianning) Ding <jnd@chromium.org>
Commit-Queue: Jonathan Wright <jonathan.wright@arm.com>
Cr-Commit-Position: refs/heads/master@{#712569}

build/config/compiler/BUILD.gn

@@ -2217,10 +2217,10 @@ config("afdo") {
     cflags = []
     if (clang_emit_debug_info_for_profiling) {
       # Add the following flags to generate debug info for profiling.
-      cflags += [
-        "-fdebug-info-for-profiling",
-        "-gline-tables-only",
-      ]
+      cflags += [ "-gline-tables-only" ]
+      if (!is_nacl) {
+        cflags += [ "-fdebug-info-for-profiling" ]
+      }
     }
     if (_clang_sample_profile != "") {
       rebased_clang_sample_profile =