libgo patch committed: Avoid duplicate function declarations in syscall

[Ian Lance Taylor]

This patch from Peter Collingbourne avoids duplicate function
declarations in the generated libcalls.go file when building the syscall
package.  Bootstrapped and ran Go testsuite on x86_64-unknown-linux-gnu.
Committed to mainline.

Ian


diff -r 5009262c3e56 libgo/go/syscall/mksyscall.awk
--- a/libgo/go/syscall/mksyscall.awk	Thu Apr 17 16:26:57 2014 -0700
+++ b/libgo/go/syscall/mksyscall.awk	Thu Apr 17 16:30:29 2014 -0700
@@ -96,8 +96,11 @@
     cfnresult = line
 
     printf("// Automatically generated wrapper for %s/%s\n", gofnname, cfnname)
-    printf("//extern %s\n", cfnname)
-    printf("func c_%s(%s) %s\n", cfnname, cfnparams, cfnresult)
+    if (!(cfnname in cfns)) {
+        cfns[cfnname] = 1
+        printf("//extern %s\n", cfnname)
+        printf("func c_%s(%s) %s\n", cfnname, cfnparams, cfnresult)
+    }
     printf("func %s(%s) %s%s%s%s{\n",
 	   gofnname, gofnparams, gofnresults == "" ? "" : "(", gofnresults,
 	   gofnresults == "" ? "" : ")", gofnresults == "" ? "" : " ")