Enable tcmalloc on mips64el.

This change enable tcmalloc on mips64el.

BUG= nobug

R= dpranke@chromium.org

Change-Id: I6927ddf0b267caba539fc8b461d6ed0e822d6e30
Reviewed-on: https://chromium-review.googlesource.com/896967Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: 汪 清 <wangqing-hf@loongson.cn>
Cr-Commit-Position: refs/heads/master@{#533920}

build/config/allocator.gni

@@ -5,9 +5,9 @@
 import("//build/config/sanitizers/sanitizers.gni")
 
 # Temporarily disable tcmalloc on arm64 linux to get rid of compilation errors.
-if (is_android || current_cpu == "mipsel" || current_cpu == "mips64el" ||
-    is_mac || is_ios || is_asan || is_lsan || is_tsan || is_msan || is_win ||
-    is_syzyasan || is_fuchsia || (is_linux && target_cpu == "arm64")) {
+if (is_android || current_cpu == "mipsel" || is_mac || is_ios ||
+    is_asan || is_lsan || is_tsan || is_msan || is_win || is_syzyasan ||
+    is_fuchsia || (is_linux && target_cpu == "arm64")) {
   _default_allocator = "none"
 } else {
   _default_allocator = "tcmalloc"