Documented the --disable-compression option in gccld and gccas.

llvm-svn: 31892
diff --git a/llvm/docs/CommandGuide/gccas.pod b/llvm/docs/CommandGuide/gccas.pod
index 7dbfae8..779d468 100644
--- a/llvm/docs/CommandGuide/gccas.pod
+++ b/llvm/docs/CommandGuide/gccas.pod
@@ -44,6 +44,10 @@
 
 Disable all assembler-time optimization passes.
 
+=item B<-disable-compression>
+
+Do not compress the generated bytecode.
+
 =item B<--stats>
 
 Print statistics.