Fix C++ build problems introduced in 9a5a5549

Fixes the following compilation errors:
regexec.c: In function 'char* S_find_byclass(regexp*, const regnode*, char*,
const char*, regmatch_info*)':
regexec.c:1525: error: invalid conversion from 'I32 (*)(const char*, const
char*, I32)' to 'I32 (*)()'
regexec.c:1525: error: too many arguments to function
regexec.c:1527: error: invalid conversion from 'I32 (*)(const char*, const
char*, I32)' to 'I32 (*)()'
regexec.c:1527: error: too many arguments to function

2 files changed, 3 insertions, 2 deletions

diff --git a/perl.h b/perl.h
index 4f66da2cc3..901e33e4b6 100644
--- a/perl.h
+++ b/perl.h
@@ -4905,6 +4905,7 @@ typedef char*   (*re_intuit_start_t) (pTHX_ regexp *prog, SV *sv,
 typedef SV*	(*re_intuit_string_t) (pTHX_ regexp *prog);
 typedef void	(*regfree_t) (pTHX_ struct regexp* r);
 typedef regexp* (*regdupe_t) (pTHX_ const regexp* r, CLONE_PARAMS *param);
+typedef I32     (*re_fold_t)(const char *, char const *, I32);
 
 typedef void (*DESTRUCTORFUNC_NOCONTEXT_t) (void*);
 typedef void (*DESTRUCTORFUNC_t) (pTHX_ void*);
diff --git a/regexec.c b/regexec.c
index 129b297d44..ff76c845a4 100644
--- a/regexec.c
+++ b/regexec.c
@@ -1245,7 +1245,7 @@ s += len
 
 #define REXEC_FBC_EXACTISH_SCAN(CoNd)                     \
 STMT_START {                                              \
-    I32 (*folder)();                                      \
+    re_fold_t folder;                                   \
     switch (OP(c)) {                                      \
 	case EXACTFU: folder = foldEQ_latin1; break;      \
 	case EXACTFL: folder = foldEQ_locale; break;      \
@@ -3558,7 +3558,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
 	    break;
 	    }
 	case EXACTFL: {
-	    I32 (*folder)();                                      \
+	    re_fold_t folder;
 	    const U8 * fold_array;
 	    const char * s;