GN(android) Don't enable --gc-sections in debug mode.

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 8f827de89ee008c3f7d6555011f72d38d04fcde9..b7d82a4687b72622526eb37c3334042756e9c5ef 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -1159,7 +1159,10 @@ config("no_optimize") {
     if (!using_sanitizer) {
       cflags += [ "-fomit-frame-pointer" ]
     }
-    ldflags = common_optimize_on_ldflags
+
+    # Don't use gc-sections since it can cause links to succeed when they
+    # actually shouldn't. http://crbug.com/159847
+    ldflags = common_optimize_on_ldflags - [ "-Wl,--gc-sections" ]
   } else {
     cflags = [ "-O0" ]
     ldflags = []