Sync our regex code with upstream changes since last time we did this, which

was Tcl 8.4.8.  The main changes are to remove the never-fully-implemented
code for multi-character collating elements, and to const-ify some stuff a
bit more fully.  In combination with the recent security patch, this commit
brings us into line with Tcl 8.5.0.

Note that I didn't make any effort to duplicate a lot of cosmetic changes
that they made to bring their copy into line with their own style
guidelines, such as adding braces around single-line IF bodies.  Most of
those we either had done already (such as ANSI-fication of function headers)
or there is no point because pgindent would undo the change anyway.

src/include/regex/regcustom.h

@@ -25,7 +25,7 @@
  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
- * $PostgreSQL: pgsql/src/include/regex/regcustom.h,v 1.6 2007/10/06 16:01:51 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/regex/regcustom.h,v 1.7 2008/02/14 17:33:37 tgl Exp $
  */
 
 /* headers if any */
@@ -47,9 +47,9 @@
 /* internal character type and related */
 typedef pg_wchar chr;			/* the type itself */
 typedef unsigned uchr;			/* unsigned type that will hold a chr */
-typedef int celt;				/* type to hold chr, MCCE number, or NOCELT */
+typedef int celt;				/* type to hold chr, or NOCELT */
 
-#define NOCELT	(-1)			/* celt value which is not valid chr or MCCE */
+#define NOCELT	(-1)			/* celt value which is not valid chr */
 #define CHR(c)	((unsigned char) (c))	/* turn char literal into chr literal */
 #define DIGITVAL(c) ((c)-'0')	/* turn chr digit into its value */
 #define CHRBITS 32				/* bits in a chr; must not use sizeof */