Move sanitizer and symbol flags out of BUILDCONFIG

build/config/compiler/compiler.gni

Index: build/config/compiler/compiler.gni
diff --git a/build/config/compiler/compiler.gni b/build/config/compiler/compiler.gni
new file mode 100644
index 0000000000000000000000000000000000000000..d5db930dab419abdc41ceaf4e148f5a7239c759b
--- /dev/null
+++ b/build/config/compiler/compiler.gni
@@ -0,0 +1,30 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("//build/config/sanitizers/sanitizers.gni")
+
+declare_args() {
+  # How many symbols to include in the build. This affects the performance of
+  # the build since the symbols are large and dealing with them is slow.
+  #   2 means regular build with symbols.
+  #   1 means minimal symbols, usually enough for backtraces only.
+  #   0 means no symbols.
+  #   -1 means auto-set according to debug/release and platform.
+  symbol_level = -1
+}
+
+# If it wasn't manually set, set to an appropriate default.
+assert(symbol_level >= -1 && symbol_level <= 2, "Invalid symbol_level")
+if (symbol_level == -1) {
+  # Linux is slowed by having symbols as part of the target binary, whereas
+  # Mac and Windows have them separate, so in Release Linux, default them off.
+  if (is_debug || !is_linux) {
+    symbol_level = 2
+  } else if (is_asan || is_lsan || is_tsan || is_msan) {
+    # Sanitizers require symbols for filename suppressions to work.
+    symbol_level = 1
+  } else {
+    symbol_level = 0
+  }
+}