Mechanical conversion to use prefixcmp()

This mechanically converts strncmp() to use prefixcmp(), but only when
the parameters match specific patterns, so that they can be verified
easily.  Leftover from this will be fixed in a separate step, including
idiotic conversions like

    if (!strncmp("foo", arg, 3))

  =>

    if (!(-prefixcmp(arg, "foo")))

This was done by using this script in px.perl

   #!/usr/bin/perl -i.bak -p
   if (/strncmp\(([^,]+), "([^\\"]*)", (\d+)\)/ && (length($2) == $3)) {
           s|strncmp\(([^,]+), "([^\\"]*)", (\d+)\)|prefixcmp($1, "$2")|;
   }
   if (/strncmp\("([^\\"]*)", ([^,]+), (\d+)\)/ && (length($1) == $3)) {
           s|strncmp\("([^\\"]*)", ([^,]+), (\d+)\)|(-prefixcmp($2, "$1"))|;
   }

and running:

   $ git grep -l strncmp -- '*.c' | xargs perl px.perl

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/daemon.c b/daemon.c
index 66f8d6f..cdbc23f 100644
--- a/daemon.c
+++ b/daemon.c
@@ -286,7 +286,7 @@
 
 static int git_daemon_config(const char *var, const char *value)
 {
-	if (!strncmp(var, "daemon.", 7) &&
+	if (!prefixcmp(var, "daemon.") &&
 	    !strcmp(var + 7, service_looking_at->config_name)) {
 		service_enabled = git_config_bool(var, value);
 		return 0;
@@ -562,7 +562,7 @@
 	for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 		struct daemon_service *s = &(daemon_service[i]);
 		int namelen = strlen(s->name);
-		if (!strncmp("git-", line, 4) &&
+		if (!(-prefixcmp(line, "git-")) &&
 		    !strncmp(s->name, line + 4, namelen) &&
 		    line[namelen + 4] == ' ') {
 			/*
@@ -1011,7 +1011,7 @@
 	for (i = 1; i < argc; i++) {
 		char *arg = argv[i];
 
-		if (!strncmp(arg, "--listen=", 9)) {
+		if (!prefixcmp(arg, "--listen=")) {
 		    char *p = arg + 9;
 		    char *ph = listen_addr = xmalloc(strlen(arg + 9) + 1);
 		    while (*p)
@@ -1019,7 +1019,7 @@
 		    *ph = 0;
 		    continue;
 		}
-		if (!strncmp(arg, "--port=", 7)) {
+		if (!prefixcmp(arg, "--port=")) {
 			char *end;
 			unsigned long n;
 			n = strtoul(arg+7, &end, 0);
@@ -1045,11 +1045,11 @@
 			export_all_trees = 1;
 			continue;
 		}
-		if (!strncmp(arg, "--timeout=", 10)) {
+		if (!prefixcmp(arg, "--timeout=")) {
 			timeout = atoi(arg+10);
 			continue;
 		}
-		if (!strncmp(arg, "--init-timeout=", 15)) {
+		if (!prefixcmp(arg, "--init-timeout=")) {
 			init_timeout = atoi(arg+15);
 			continue;
 		}
@@ -1057,11 +1057,11 @@
 			strict_paths = 1;
 			continue;
 		}
-		if (!strncmp(arg, "--base-path=", 12)) {
+		if (!prefixcmp(arg, "--base-path=")) {
 			base_path = arg+12;
 			continue;
 		}
-		if (!strncmp(arg, "--interpolated-path=", 20)) {
+		if (!prefixcmp(arg, "--interpolated-path=")) {
 			interpolated_path = arg+20;
 			continue;
 		}
@@ -1073,11 +1073,11 @@
 			user_path = "";
 			continue;
 		}
-		if (!strncmp(arg, "--user-path=", 12)) {
+		if (!prefixcmp(arg, "--user-path=")) {
 			user_path = arg + 12;
 			continue;
 		}
-		if (!strncmp(arg, "--pid-file=", 11)) {
+		if (!prefixcmp(arg, "--pid-file=")) {
 			pid_file = arg + 11;
 			continue;
 		}
@@ -1086,27 +1086,27 @@
 			log_syslog = 1;
 			continue;
 		}
-		if (!strncmp(arg, "--user=", 7)) {
+		if (!prefixcmp(arg, "--user=")) {
 			user_name = arg + 7;
 			continue;
 		}
-		if (!strncmp(arg, "--group=", 8)) {
+		if (!prefixcmp(arg, "--group=")) {
 			group_name = arg + 8;
 			continue;
 		}
-		if (!strncmp(arg, "--enable=", 9)) {
+		if (!prefixcmp(arg, "--enable=")) {
 			enable_service(arg + 9, 1);
 			continue;
 		}
-		if (!strncmp(arg, "--disable=", 10)) {
+		if (!prefixcmp(arg, "--disable=")) {
 			enable_service(arg + 10, 0);
 			continue;
 		}
-		if (!strncmp(arg, "--allow-override=", 17)) {
+		if (!prefixcmp(arg, "--allow-override=")) {
 			make_service_overridable(arg + 17, 1);
 			continue;
 		}
-		if (!strncmp(arg, "--forbid-override=", 18)) {
+		if (!prefixcmp(arg, "--forbid-override=")) {
 			make_service_overridable(arg + 18, 0);
 			continue;
 		}