Make report() from usage.c public as vreportf() and use it.

There exist already a number of static functions named 'report', therefore,
the function name was changed.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/usage.c b/usage.c
index 79856a2..ec4cf53 100644
--- a/usage.c
+++ b/usage.c
@@ -5,7 +5,7 @@
  */
 #include "git-compat-util.h"
 
-static void report(const char *prefix, const char *err, va_list params)
+void vreportf(const char *prefix, const char *err, va_list params)
 {
 	char msg[4096];
 	vsnprintf(msg, sizeof(msg), err, params);
@@ -14,24 +14,24 @@
 
 static NORETURN void usage_builtin(const char *err, va_list params)
 {
-	report("usage: ", err, params);
+	vreportf("usage: ", err, params);
 	exit(129);
 }
 
 static NORETURN void die_builtin(const char *err, va_list params)
 {
-	report("fatal: ", err, params);
+	vreportf("fatal: ", err, params);
 	exit(128);
 }
 
 static void error_builtin(const char *err, va_list params)
 {
-	report("error: ", err, params);
+	vreportf("error: ", err, params);
 }
 
 static void warn_builtin(const char *warn, va_list params)
 {
-	report("warning: ", warn, params);
+	vreportf("warning: ", warn, params);
 }
 
 /* If we are in a dlopen()ed .so write to a global variable would segfault