Merge pull request swiftlang#221 from apple/das-disable-linux-membarrier-include

remove unused dependency on linux/membarrier.h for intel to fix CI build

Author: das

Diff for: INSTALL.md

@@ -152,7 +152,7 @@ on Ubuntu; currently supported versions are 14.04, 15.10 and 16.04.
 
 1. The first thing to do is install required packages:
 
-    `sudo apt-get install autoconf libtool pkg-config clang systemtap-sdt-dev libbsd-dev`
+    `sudo apt-get install autoconf libtool pkg-config clang systemtap-sdt-dev libbsd-dev linux-libc-dev`
 
     Note: compiling libdispatch requires clang 3.8 or better and
 the gold linker. If the default clang on your Ubuntu version is

Diff for: src/shims/lock.h

@@ -89,7 +89,9 @@ _dispatch_lock_has_failed_trylock(dispatch_lock lock_value)
 
 #elif defined(__linux__)
 #include <linux/futex.h>
+#if !defined(__x86_64__) && !defined(__i386__)
 #include <linux/membarrier.h>
+#endif
 #include <unistd.h>
 #include <sys/syscall.h>   /* For SYS_xxx definitions */