Add support for cortex-a53 in bionic.

allows -mcpu=cortex-a53 to be passed as part of a command line.

Change-Id: Id4203a9fd197f4c3b661bad21ac58c32819fd687
diff --git a/libc/arch-arm/cortex-a53/cortex-a53.mk b/libc/arch-arm/cortex-a53/cortex-a53.mk
new file mode 100644
index 0000000..b5c337c
--- /dev/null
+++ b/libc/arch-arm/cortex-a53/cortex-a53.mk
@@ -0,0 +1 @@
+include bionic/libc/arch-arm/cortex-a7/cortex-a7.mk
diff --git a/libc/arch-arm64/cortex-a53/cortex-a53.mk b/libc/arch-arm64/cortex-a53/cortex-a53.mk
new file mode 100644
index 0000000..676e886
--- /dev/null
+++ b/libc/arch-arm64/cortex-a53/cortex-a53.mk
@@ -0,0 +1 @@
+include bionic/libc/arch-arm64/generic/generic.mk