runtime: introduce mvifdiff.sh script to replace GCC's move-if-change

This goes towards making libgo more self-contained.

From-SVN: r218198

libgo/Makefile.am

@@ -1007,7 +1007,7 @@ s-version: Makefile
 	echo 'const theVersion = "'`$(GOC) --version | sed 1q`'"' >> version.go.tmp
 	echo 'const theGoarch = "'$(GOARCH)'"' >> version.go.tmp
 	echo 'const theGoos = "'$(GOOS)'"' >> version.go.tmp
-	$(SHELL) $(srcdir)/../move-if-change version.go.tmp version.go
+	$(SHELL) $(srcdir)/mvifdiff.sh version.go.tmp version.go
 	$(STAMP) $@
 
 go_sort_files = \
@@ -1791,14 +1791,14 @@ s-libcalls: libcalls-list go/syscall/mksyscall.awk $(go_base_syscall_files)
 	rm -f libcalls.go.tmp
 	files=`echo $^ | sed -e 's/libcalls-list//' -e 's|[^ ]*go/syscall/mksyscall.awk||'`; \
 	$(AWK) -f $(srcdir)/go/syscall/mksyscall.awk $${files} > libcalls.go.tmp
-	$(SHELL) $(srcdir)/../move-if-change libcalls.go.tmp libcalls.go
+	$(SHELL) $(srcdir)/mvifdiff.sh libcalls.go.tmp libcalls.go
 	$(STAMP) $@
 
 libcalls-list: s-libcalls-list; @true
 s-libcalls-list: Makefile
 	rm -f libcalls-list.tmp
 	echo $(go_base_syscall_files) > libcalls-list.tmp
-	$(SHELL) $(srcdir)/../move-if-change libcalls-list.tmp libcalls-list
+	$(SHELL) $(srcdir)/mvifdiff.sh libcalls-list.tmp libcalls-list
 	$(STAMP) $@
 
 syscall_arch.go: s-syscall_arch; @true
@@ -1807,13 +1807,13 @@ s-syscall_arch: Makefile
 	echo "package syscall" > syscall_arch.go.tmp
 	echo 'const ARCH = "'$(GOARCH)'"' >> syscall_arch.go.tmp
 	echo 'const OS = "'$(GOOS)'"' >> syscall_arch.go.tmp
-	$(SHELL) $(srcdir)/../move-if-change syscall_arch.go.tmp syscall_arch.go
+	$(SHELL) $(srcdir)/mvifdiff.sh syscall_arch.go.tmp syscall_arch.go
 	$(STAMP) $@
 
 sysinfo.go: s-sysinfo; @true
 s-sysinfo: $(srcdir)/mksysinfo.sh config.h
 	CC="$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(OSCFLAGS)" $(SHELL) $(srcdir)/mksysinfo.sh
-	$(SHELL) $(srcdir)/../move-if-change tmp-sysinfo.go sysinfo.go
+	$(SHELL) $(srcdir)/mvifdiff.sh tmp-sysinfo.go sysinfo.go
 	$(STAMP) $@
 
 # The epoll struct has an embedded union and is packed on x86_64,
@@ -1841,7 +1841,7 @@ s-epoll: Makefile
 	   exit 1; ;; \
 	esac
 	echo '}' >> epoll.go.tmp
-	$(SHELL) $(srcdir)/../move-if-change epoll.go.tmp epoll.go
+	$(SHELL) $(srcdir)/mvifdiff.sh epoll.go.tmp epoll.go
 	$(STAMP) $@
 
 if LIBGO_IS_LINUX

libgo/Makefile.in

@@ -4392,7 +4392,7 @@ s-version: Makefile
 	echo 'const theVersion = "'`$(GOC) --version | sed 1q`'"' >> version.go.tmp
 	echo 'const theGoarch = "'$(GOARCH)'"' >> version.go.tmp
 	echo 'const theGoos = "'$(GOOS)'"' >> version.go.tmp
-	$(SHELL) $(srcdir)/../move-if-change version.go.tmp version.go
+	$(SHELL) $(srcdir)/mvifdiff.sh version.go.tmp version.go
 	$(STAMP) $@
 
 libcalls.go: s-libcalls; @true
@@ -4400,14 +4400,14 @@ s-libcalls: libcalls-list go/syscall/mksyscall.awk $(go_base_syscall_files)
 	rm -f libcalls.go.tmp
 	files=`echo $^ | sed -e 's/libcalls-list//' -e 's|[^ ]*go/syscall/mksyscall.awk||'`; \
 	$(AWK) -f $(srcdir)/go/syscall/mksyscall.awk $${files} > libcalls.go.tmp
-	$(SHELL) $(srcdir)/../move-if-change libcalls.go.tmp libcalls.go
+	$(SHELL) $(srcdir)/mvifdiff.sh libcalls.go.tmp libcalls.go
 	$(STAMP) $@
 
 libcalls-list: s-libcalls-list; @true
 s-libcalls-list: Makefile
 	rm -f libcalls-list.tmp
 	echo $(go_base_syscall_files) > libcalls-list.tmp
-	$(SHELL) $(srcdir)/../move-if-change libcalls-list.tmp libcalls-list
+	$(SHELL) $(srcdir)/mvifdiff.sh libcalls-list.tmp libcalls-list
 	$(STAMP) $@
 
 syscall_arch.go: s-syscall_arch; @true
@@ -4416,13 +4416,13 @@ s-syscall_arch: Makefile
 	echo "package syscall" > syscall_arch.go.tmp
 	echo 'const ARCH = "'$(GOARCH)'"' >> syscall_arch.go.tmp
 	echo 'const OS = "'$(GOOS)'"' >> syscall_arch.go.tmp
-	$(SHELL) $(srcdir)/../move-if-change syscall_arch.go.tmp syscall_arch.go
+	$(SHELL) $(srcdir)/mvifdiff.sh syscall_arch.go.tmp syscall_arch.go
 	$(STAMP) $@
 
 sysinfo.go: s-sysinfo; @true
 s-sysinfo: $(srcdir)/mksysinfo.sh config.h
 	CC="$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(OSCFLAGS)" $(SHELL) $(srcdir)/mksysinfo.sh
-	$(SHELL) $(srcdir)/../move-if-change tmp-sysinfo.go sysinfo.go
+	$(SHELL) $(srcdir)/mvifdiff.sh tmp-sysinfo.go sysinfo.go
 	$(STAMP) $@
 
 # The epoll struct has an embedded union and is packed on x86_64,
@@ -4450,7 +4450,7 @@ s-epoll: Makefile
 	   exit 1; ;; \
 	esac
 	echo '}' >> epoll.go.tmp
-	$(SHELL) $(srcdir)/../move-if-change epoll.go.tmp epoll.go
+	$(SHELL) $(srcdir)/mvifdiff.sh epoll.go.tmp epoll.go
 	$(STAMP) $@
 
 @go_include@ bufio.lo.dep

libgo/mvifdiff.sh

+#!/bin/sh
+
+# Copyright 2014 The Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+# The mvifdiff.sh script works like the mv(1) command, except
+# that it does not touch the destination file if its contents
+# are the same as the source file.
+
+if cmp -s "$1" "$2" ; then
+  rm "$1"
+else
+  mv "$1" "$2"
+fi