GN: Add back -fPIC for a few things

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 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/android/config.gni")
 if (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }
 if (current_cpu == "mipsel" || current_cpu == "mips64el") {
   import("//build/config/mips.gni")
@@ skipping 281 matching lines @@
   # Linux/Android common flags setup.
   # ---------------------------------
   if (is_linux || is_android) {
     ldflags += [
       "-Wl,-z,noexecstack",
       "-Wl,-z,now",
       "-Wl,-z,relro",
     ]
   }
 
+  # We need -fPIC:
+  # 1. On ARM and MIPS for tcmalloc.
+  # 2. On Android.
+  # 3. When using the sanitizers.
+  # Otherwise there is a performance hit, in particular on ia32.
+  if (is_android || is_asan || is_lsan || is_msan || is_tsan ||
+      (is_linux && (current_cpu == "arm" || current_cpu == "mipsel"))) {
+    cflags += [ "-fPIC" ]
+    ldflags += [ "-fPIC" ]
+  }
+
   # Linux-specific compiler flags setup.
   # ------------------------------------
   if (is_linux) {
     cflags += [ "-pthread" ]
     ldflags += [ "-pthread" ]
   }
 
   # Clang-specific compiler flags setup.
   # ------------------------------------
   if (is_clang) {
@@ skipping 448 matching lines @@
       cflags = [ "/Zi" ]  # Produce PDB file, no edit and continue.
     }
     ldflags = [ "/DEBUG" ]
   } else {
     cflags = [
       "-g3",
       "-ggdb3",
     ]
   }
 }