libgo: fix improperly mangled linker symbol directive

    
    Fix asm name directive for the C version of log/syslog.syslog_c,
    which didn't get included in the recent name mangling change.
    
    Reviewed-on: https://go-review.googlesource.com/c/145017

From-SVN: r265533

gcc/go/gofrontend/MERGE

-0a58bd7d820dac8931e8da5b291f19c3c7e6bee3
+ad50884d2a4b653f7f20edc8b441fe6ad6570d55
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/log/syslog/syslog_c.c

@@ -12,7 +12,7 @@
    can't represent a C varargs function in Go.  */
 
 void syslog_c(intgo, const char*)
-  __asm__ (GOSYM_PREFIX "log_syslog.syslog_c");
+  __asm__ (GOSYM_PREFIX "log..z2fsyslog.syslog_c");
 
 void
 syslog_c (intgo priority, const char *msg)