strbuf: add xstrdup_toupper()

Create a copy of an existing string and make all characters upper case.
Similar xstrdup_tolower().

This function is used in a subsequent commit.
Signed-off-by: NLars Schneider <larsxschneider@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

strbuf.c

@@ -784,6 +784,18 @@ char *xstrdup_tolower(const char *string)
 	return result;
 }
 
+char *xstrdup_toupper(const char *string)
+{
+	char *result;
+	size_t len, i;
+
+	len = strlen(string);
+	result = xmallocz(len);
+	for (i = 0; i < len; i++)
+		result[i] = toupper(string[i]);
+	return result;
+}
+
 char *xstrvfmt(const char *fmt, va_list ap)
 {
 	struct strbuf buf = STRBUF_INIT;

strbuf.h

@@ -607,6 +607,7 @@ __attribute__((format (printf,2,3)))
 extern int fprintf_ln(FILE *fp, const char *fmt, ...);
 
 char *xstrdup_tolower(const char *);
+char *xstrdup_toupper(const char *);
 
 /**
  * Create a newly allocated string using printf format. You can do this easily