Fix building on armv7

Author: hpux735

configure.ac

@@ -147,6 +147,12 @@ AC_ARG_WITH([swift-toolchain],
    case $target_os in
       linux*)
 	    os_string="linux"
+	    case $target_cpu in
+		    armv7l*)
+			target_cpu="armv7"
+			;;
+			*)
+            esac
 	    ;;
 	  *)
         os_string=$target_os

dispatch/dispatch.h

@@ -49,9 +49,11 @@
 
 #if defined(__linux__) && defined(__has_feature)
 #if __has_feature(modules)
+#if !defined(__arm__)
 #include <stdio.h> // for off_t (to match Glibc.modulemap)
 #endif
 #endif
+#endif
 
 #define DISPATCH_API_VERSION 20160712
 

src/io.c

@@ -24,6 +24,10 @@
 #define DISPATCH_IO_DEBUG DISPATCH_DEBUG
 #endif
 
+#ifndef PAGE_SIZE
+#define PAGE_SIZE getpagesize()
+#endif
+
 #if DISPATCH_DATA_IS_BRIDGED_TO_NSDATA
 #define _dispatch_io_data_retain(x) _dispatch_objc_retain(x)
 #define _dispatch_io_data_release(x) _dispatch_objc_release(x)