[Mac/GN] Compile with -fno-standalone-debug if enable_dsyms=true.

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 4b624cfe3d107f35edc763d7bb22e54819e70f3b..30d6b465924117fe6f52423ad396b215c459f7e1 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -1487,6 +1487,14 @@ config("symbols") {
   } else {
     if (is_mac || is_ios) {
       cflags = [ "-gdwarf-2" ]
+      if (enable_dsyms) {

[Dirk Pranke, 2016/06/27 23:44:57]

you need to import("//build/config/mac/symbols.gni") first.

Or, probably better, just get rid of mac/symbols.gni and move those two args
into compiler.gni since you end up having to include both of them regardless.

+        # If generating dSYMs, specify -fno-standalone-debug. This was
+        # originally specified for https://crbug.com/479841 because dsymutil
+        # could not handle a 4GB dSYM file. But dsymutil from Xcodes prior to
+        # version 7 also produce debug data that is incompatible with Breakpad

[Mark Mentovai, 2016/06/27 23:43:46]

produces

+        # dump_syms, so this is still required (https://crbug.com/622406).
+        cflags += [ "-fno-standalone-debug" ]
+      }
     } else {
       cflags = [ "-g2" ]
     }