Replace calls to strbuf_init(&foo, 0) with STRBUF_INIT initializer

Many call sites use strbuf_init(&foo, 0) to initialize local
strbuf variable "foo" which has not been accessed since its
declaration. These can be replaced with a static initialization
using the STRBUF_INIT macro which is just as readable, saves a
function call, and takes up fewer lines.

Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

git.c

@@ -389,10 +389,9 @@ static void handle_internal_command(int argc, const char **argv)
 
 static void execv_dashed_external(const char **argv)
 {
-	struct strbuf cmd;
+	struct strbuf cmd = STRBUF_INIT;
 	const char *tmp;
 
-	strbuf_init(&cmd, 0);
 	strbuf_addf(&cmd, "git-%s", argv[0]);
 
 	/*