change the names to have .sh suffixes.
also fix the comments in the generated files.

R=rsc
DELTA=949  (470 added, 465 deleted, 14 changed)
OCL=33197
CL=33201
diff --git a/src/pkg/syscall/zerrors_darwin_386.go b/src/pkg/syscall/zerrors_darwin_386.go
index bc2d176..a19c99d 100644
--- a/src/pkg/syscall/zerrors_darwin_386.go
+++ b/src/pkg/syscall/zerrors_darwin_386.go
@@ -1,4 +1,4 @@
-// mkerrors
+// mkerrors.sh
 // MACHINE GENERATED BY THE COMMAND ABOVE; DO NOT EDIT
 
 // godefs -gsyscall _errors.c