libgo: add additional references in sysinfo.c

[Ian Lance Taylor via Gcc-patches]

This libgo patch by Than McIntosh adds a few more explicit references
to enumeration constants (RUSAGE_SELF, DT_UNKNOWN) in sysinfo.c to
insure that their hosting enums are emitted into DWARF, when using a
clang host compiler during the gollvm build.  Bootstrapped and ran Go
testsuite on x86_64-pc-linux-gnu.  Committed to mainline.

Ian

d04a5acb18867932d937351ab9804d6cfc83c5f0
diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index dc63f4a696a..df9d2118dfd 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-b75a139fcc7c56988ce2d5b3a2b9e274eb521b0d
+a47485cd0e9ce6a8b3e88e53ccc0a440f0bd4351
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/libgo/sysinfo.c b/libgo/sysinfo.c
index 0692fd41eb7..76405597128 100644
--- a/libgo/sysinfo.c
+++ b/libgo/sysinfo.c
@@ -316,6 +316,7 @@ enum {
 SREF(dirent);
 SREF(dirent64);
 OTREF(DIR);
+EREF(DT_UNKNOWN);
 
 // From fcntl.h
 SREF(flock);
@@ -437,6 +438,7 @@ SREF(rusage);
 SREF(rlimit64);
 EREF(RLIMIT_NOFILE);
 EREF(PRIO_USER);
+EREF(RUSAGE_SELF);
 
 // From sys/select.h
 TREF(fd_set);