Turn on -Wold-style-cast and fix the errors.

A couple of dodgy cases where we cast away const, but otherwise pretty boring.

Change-Id: Ibc39ebd525377792b5911464be842121c20f03b9
diff --git a/libc/Android.mk b/libc/Android.mk
index e96bcff..2f534c3 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -862,7 +862,7 @@
 LOCAL_CLANG_ASFLAGS_arm64 += -no-integrated-as
 
 LOCAL_CONLYFLAGS := $(libc_common_conlyflags)
-LOCAL_CPPFLAGS := $(libc_common_cppflags)
+LOCAL_CPPFLAGS := $(libc_common_cppflags) -Wold-style-cast
 LOCAL_C_INCLUDES := $(libc_common_c_includes) bionic/libstdc++/include
 LOCAL_MODULE := libc_bionic
 LOCAL_CLANG := $(use_clang)