Removed memory leaks from interpolation table uses.

Clarified that parse_extra_args()s results in interpolation
table entries.  Removed a few trailing whitespace occurrences.

Signed-off-by: Jon Loeliger <jdl@jdl.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

interpolate.c

@@ -4,9 +4,35 @@
 
 #include <string.h>
 
+#include "git-compat-util.h"
 #include "interpolate.h"
 
 
+void interp_set_entry(struct interp *table, int slot, char *value)
+{
+	char *oldval = table[slot].value;
+	char *newval = value;
+
+	if (oldval)
+		free(oldval);
+
+	if (value)
+		newval = xstrdup(value);
+
+	table[slot].value = newval;
+}
+
+
+void interp_clear_table(struct interp *table, int ninterps)
+{
+	int i;
+
+	for (i = 0; i < ninterps; i++) {
+		interp_set_entry(table, i, NULL);
+	}
+}
+
+
 /*
  * Convert a NUL-terminated string in buffer orig
  * into the supplied buffer, result, whose length is reslen,