jemalloc: switch to latest C standard

Following upstream, which switched to C11
with the 4.3 release, this change switches
the Android specific makefile to use the
defaults.

Test: Built arm, arm64, x86, and x86_64.

Change-Id: I2e4a6d0f5c5fc95d5d6485319ab81f6bd01192ff
Signed-off-by: Alex Naidis <alex.naidis@linux.com>
diff --git a/Android.bp b/Android.bp
index 38aacf8..f8d205b 100644
--- a/Android.bp
+++ b/Android.bp
@@ -15,7 +15,6 @@
 //
 
 common_cflags = [
-    "-std=gnu99",
     "-D_REENTRANT",
     "-fvisibility=hidden",
     "-Wno-unused-parameter",