mingw.c: move definition of mingw_getenv down

We want to use static lookup_env() in a subsequent change.

At first sight, this change looks innocent. But it is not due to the
#undef getenv. There is one caller of getenv between the old location and
the new location whose behavior could change. But as can be seen from the
defintion of mingw_getenv, the behavior for this caller does not change
substantially.

To ensure consistent behavior in the future, change all getenv callers
in mingw.c to use mingw_getenv.

With this patch, this is not a big deal, yet, but with the subsequent
change, where we teach getenv to do a case-sensitive lookup, the behavior
of all call sites is changed.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

compat/mingw.c

@@ -178,7 +178,7 @@ static int ask_yes_no_if_possible(const char *format, ...)
 	vsnprintf(question, sizeof(question), format, args);
 	va_end(args);
 
-	if ((retry_hook[0] = getenv("GIT_ASK_YESNO"))) {
+	if ((retry_hook[0] = mingw_getenv("GIT_ASK_YESNO"))) {
 		retry_hook[1] = question;
 		return !run_command_v_opt(retry_hook, 0);
 	}
@@ -599,19 +599,6 @@ char *mingw_getcwd(char *pointer, int len)
 	return ret;
 }
 
-#undef getenv
-char *mingw_getenv(const char *name)
-{
-	char *result = getenv(name);
-	if (!result && !strcmp(name, "TMPDIR")) {
-		/* on Windows it is TMP and TEMP */
-		result = getenv("TMP");
-		if (!result)
-			result = getenv("TEMP");
-	}
-	return result;
-}
-
 /*
  * See http://msdn2.microsoft.com/en-us/library/17w5ykft(vs.71).aspx
  * (Parsing C++ Command-Line Arguments)
@@ -711,7 +698,7 @@ static const char *parse_interpreter(const char *cmd)
  */
 static char **get_path_split(void)
 {
-	char *p, **path, *envpath = getenv("PATH");
+	char *p, **path, *envpath = mingw_getenv("PATH");
 	int i, n = 0;
 
 	if (!envpath || !*envpath)
@@ -1128,6 +1115,19 @@ char **make_augmented_environ(const char *const *vars)
 	return env;
 }
 
+#undef getenv
+char *mingw_getenv(const char *name)
+{
+	char *result = getenv(name);
+	if (!result && !strcmp(name, "TMPDIR")) {
+		/* on Windows it is TMP and TEMP */
+		result = getenv("TMP");
+		if (!result)
+			result = getenv("TEMP");
+	}
+	return result;
+}
+
 /*
  * Note, this isn't a complete replacement for getaddrinfo. It assumes
  * that service contains a numerical port, or that it is null. It