Many files:

Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
my_regex.h:
  Rename: regex/regex.h -> regex/my_regex.h


client/mysqltest.c:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
os2/MySQL-Source.icc:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/Makefile.am:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/debug.c:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/debug.ih:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/engine.c:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/engine.ih:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/main.c:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/main.ih:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/regcomp.c:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/regerror.c:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/regerror.ih:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/my_regex.h:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/regexec.c:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/regfree.c:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
regex/reginit.c:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
sql/item_cmpfunc.cc:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
sql/item_cmpfunc.h:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.
sql/mysqld.cc:
  Prefix regex functions/types with "my_" as our
  library is not compatible with normal regex lib.

regex/my_regex.h

@@ -0,0 +1,86 @@
+#ifndef _REGEX_H_
+#define	_REGEX_H_	/* never again */
+/* ========= begin header generated by ./mkh ========= */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "m_ctype.h"
+
+/* === regex2.h === */
+#ifdef _WIN64
+typedef __int64 regoff_t;
+#else
+typedef off_t regoff_t;
+#endif
+struct re_guts;			/* none of your business :-) */
+typedef struct {
+	int re_magic;
+	size_t re_nsub;		/* number of parenthesized subexpressions */
+	const char *re_endp;	/* end pointer for REG_PEND */
+	struct re_guts *re_g;	/* none of your business :-) */
+	CHARSET_INFO *charset;	/* For ctype things */
+} my_regex_t;
+typedef struct {
+	regoff_t rm_so;		/* start of match */
+	regoff_t rm_eo;		/* end of match */
+} my_regmatch_t;
+
+
+/* === regcomp.c === */
+extern int my_regcomp(my_regex_t *, const char *, int, CHARSET_INFO *charset);
+#define	REG_BASIC	0000
+#define	REG_EXTENDED	0001
+#define	REG_ICASE	0002
+#define	REG_NOSUB	0004
+#define	REG_NEWLINE	0010
+#define	REG_NOSPEC	0020
+#define	REG_PEND	0040
+#define	REG_DUMP	0200
+
+
+/* === regerror.c === */
+#define	REG_NOMATCH	 1
+#define	REG_BADPAT	 2
+#define	REG_ECOLLATE	 3
+#define	REG_ECTYPE	 4
+#define	REG_EESCAPE	 5
+#define	REG_ESUBREG	 6
+#define	REG_EBRACK	 7
+#define	REG_EPAREN	 8
+#define	REG_EBRACE	 9
+#define	REG_BADBR	10
+#define	REG_ERANGE	11
+#define	REG_ESPACE	12
+#define	REG_BADRPT	13
+#define	REG_EMPTY	14
+#define	REG_ASSERT	15
+#define	REG_INVARG	16
+#define	REG_ATOI	255	/* convert name to number (!) */
+#define	REG_ITOA	0400	/* convert number to name (!) */
+extern size_t my_regerror(int, const my_regex_t *, char *, size_t);
+
+
+/* === regexec.c === */
+extern int my_regexec(const my_regex_t *, const char *, size_t, my_regmatch_t [], int);
+#define	REG_NOTBOL	00001
+#define	REG_NOTEOL	00002
+#define	REG_STARTEND	00004
+#define	REG_TRACE	00400	/* tracing of execution */
+#define	REG_LARGE	01000	/* force large representation */
+#define	REG_BACKR	02000	/* force use of backref code */
+
+
+/* === regfree.c === */
+extern void my_regfree(my_regex_t *);
+
+/* === reginit.c === */
+
+extern void my_regex_init(CHARSET_INFO *cs);	/* Should be called for multithread progs */
+extern void my_regex_end(void);	/* If one wants a clean end */
+
+#ifdef __cplusplus
+}
+#endif
+/* ========= end header generated by ./mkh ========= */
+#endif