sh: Do IFS splitting on word in ${v+word} and ${v-word}.

The code is inspired by NetBSD sh somewhat, but different because we
preserve the old Almquist/Bourne/Korn ability to have an unquoted part in a
quoted ${v+word}. For example, "${v-"*"}" expands to $v as a single field if
v is set, but generates filenames otherwise.

Note that this is the only place where we split text literally from the
script (the similar ${v=word} assigns to v and then expands $v). The parser
must now add additional markers to allow the expansion code to know whether
arbitrary characters in substitutions are quoted.

Example:
  for i in ${$+a b c}; do echo $i; done

Exp-run done by:	pav (with some other sh(1) changes)

1 files changed, 1 insertions, 0 deletions

diff --git a/bin/sh/mksyntax.c b/bin/sh/mksyntax.c
index e4c4d14..07e8eb7 100644
--- a/bin/sh/mksyntax.c
+++ b/bin/sh/mksyntax.c
@@ -285,6 +285,7 @@ init(void)
 	syntax[base + CTLARI] = "CCTL";
 	syntax[base + CTLENDARI] = "CCTL";
 	syntax[base + CTLQUOTEMARK] = "CCTL";
+	syntax[base + CTLQUOTEEND] = "CCTL";
 }