bionic: deprecate _PATH_MEM

/dev/mem (and /dev/kmem) are not enabled in the kernels, and selinux
prevents access and makes it a rule compilation error to enable
access. No code uses the _PATH_MEM macro. Remove definition to
suppress future usage.

Bug: 19549480
Change-Id: Ie0fb0f53d43349f4fe227068e4bf8a768f620d60
diff --git a/libc/include/paths.h b/libc/include/paths.h
index 1eba536..33c2eee 100644
--- a/libc/include/paths.h
+++ b/libc/include/paths.h
@@ -39,7 +39,6 @@
 #define	_PATH_CONSOLE	"/dev/console"
 #define	_PATH_DEVNULL	"/dev/null"
 #define	_PATH_KLOG	"/proc/kmsg"
-#define	_PATH_MEM	"/dev/mem"
 
 #define	_PATH_MOUNTED	"/proc/mounts"
 #define	_PATH_TTY	"/dev/tty"