git-compat-util: convert string predicates to return bool

Since 8277dbe (git-compat-util: convert skip_{prefix,suffix}{,_mem}
to bool, 2023-12-16) a number of our string predicates have been
returning bool instead of int. Now that we've declared that experiment
a success, let's convert the return type of the case-independent
skip_iprefix() and skip_iprefix_mem() functions to match the return
type of their case-dependent equivalents. Returning bool instead of
int makes it clear that these functions are predicates.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: phillipwood

git-compat-util.h

@@ -895,35 +895,35 @@ static inline size_t xsize_t(off_t len)
  * is done via tolower(), so it is strictly ASCII (no multi-byte characters or
  * locale-specific conversions).
  */
-static inline int skip_iprefix(const char *str, const char *prefix,
+static inline bool skip_iprefix(const char *str, const char *prefix,
 			       const char **out)
 {
 	do {
 		if (!*prefix) {
 			*out = str;
-			return 1;
+			return true;
 		}
 	} while (tolower(*str++) == tolower(*prefix++));
-	return 0;
+	return false;
 }
 
 /*
  * Like skip_prefix_mem, but compare case-insensitively. Note that the
  * comparison is done via tolower(), so it is strictly ASCII (no multi-byte
  * characters or locale-specific conversions).
  */
-static inline int skip_iprefix_mem(const char *buf, size_t len,
+static inline bool skip_iprefix_mem(const char *buf, size_t len,
 				   const char *prefix,
 				   const char **out, size_t *outlen)
 {
 	do {
 		if (!*prefix) {
 			*out = buf;
 			*outlen = len;
-			return 1;
+			return true;
 		}
 	} while (len-- > 0 && tolower(*buf++) == tolower(*prefix++));
-	return 0;
+	return false;
 }
 
 static inline int strtoul_ui(char const *s, int base, unsigned int *result)