Add -Wno-error flag to avoid warnings being regarded as errors.

Author: JohnWangCH

build/config/target.gni

@@ -15,8 +15,8 @@
 declare_args() {
   # Global defines for target build. This only applies to the default toolchain.
   target_defines = []
-  target_cflags = []
-  target_cflags_cc = []
-  target_cflags_c = []
+  target_cflags = ["-Wno-error"]
+  target_cflags_cc = ["-Wno-error"]
+  target_cflags_c = ["-Wno-error"]
   target_ldflags = []
 }