libgo patch committed: Fix surrogate pairs in string([]rune)

[Ian Lance Taylor]

This patch to libgo fixes the handling of surrogate pairs when
converting a []rune value to string.  Invalid surrogate pair values
should become the replacement character in the string, as otherwise the
string will not be valid UTF-8.  I have a patch ready for the master Go
testsuite after the 1.2 release goes out.  Bootstrapped and ran Go
testsuite on x86_64-unknown-linux-gnu.  Committed to mainline and 4.8
branch.

Ian


diff -r fff3cb764986 libgo/runtime/go-int-array-to-string.c
--- a/libgo/runtime/go-int-array-to-string.c	Tue Nov 26 10:07:46 2013 -0800
+++ b/libgo/runtime/go-int-array-to-string.c	Tue Nov 26 15:13:08 2013 -0800
@@ -30,6 +30,8 @@
 
       if (v < 0 || v > 0x10ffff)
 	v = 0xfffd;
+      else if (0xd800 <= v && v <= 0xdfff)
+	v = 0xfffd;
 
       if (v <= 0x7f)
 	slen += 1;
@@ -56,6 +58,8 @@
 	 character.  */
       if (v < 0 || v > 0x10ffff)
 	v = 0xfffd;
+      else if (0xd800 <= v && v <= 0xdfff)
+	v = 0xfffd;
 
       if (v <= 0x7f)
 	*s++ = v;