[MIPS] Add atomic routines

Change-Id: I2cb20ce44dd230d222b7fc1ede2e1e3dce6e692b
diff --git a/libc/private/bionic_atomic_inline.h b/libc/private/bionic_atomic_inline.h
index 821ad39..0b348c3 100644
--- a/libc/private/bionic_atomic_inline.h
+++ b/libc/private/bionic_atomic_inline.h
@@ -53,6 +53,8 @@
 #  include <bionic_atomic_arm.h>
 #elif defined(__i386__)
 #  include <bionic_atomic_x86.h>
+#elif defined(__mips__)
+#  include <bionic_atomic_mips.h>
 #else
 #  include <bionic_atomic_gcc_builtin.h>
 #endif