sh: Fix some bugs with backquoted builtins:

- correctly handle error output in $(builtin 2>&1), clarify out1/out2 vs
  output/errout in the code
- treat all builtins as regular builtins so errors do not abort the shell
  and variable assignments do not persist
- respect the caller's INTOFF

Some bugs still exist:
- expansion errors may still abort the shell
- some side effects of expansions and builtins persist

1 files changed, 2 insertions, 2 deletions

diff --git a/bin/sh/parser.c b/bin/sh/parser.c
index b85d10ad..f8fd0ed 100644
--- a/bin/sh/parser.c
+++ b/bin/sh/parser.c
@@ -1560,8 +1560,8 @@ STATIC void
 synerror(const char *msg)
 {
 	if (commandname)
-		outfmt(&errout, "%s: %d: ", commandname, startlinno);
-	outfmt(&errout, "Syntax error: %s\n", msg);
+		outfmt(out2, "%s: %d: ", commandname, startlinno);
+	outfmt(out2, "Syntax error: %s\n", msg);
 	error((char *)NULL);
 }