Make sure to only use as much data as it was actually read

When reading a C macro, make sure to only use as much byes we actually
got and not as much as we requested.  This should not be a problem
anymore now 61c5216 fixed a too long read, but it's safer anyway.

tagmanager/ctags/get.c

@@ -722,10 +722,12 @@ extern char *getArglistFromFilePos(MIOPos startPosition, const char *tokenName)
 
 	if (pos2 > pos1)
 	{
-		result = (char *) g_malloc(sizeof(char ) * (pos2 - pos1 + 1));
-		if (result != NULL && mio_read(File.mio, result, sizeof(char), pos2 - pos1) > 0)
+		size_t len = pos2 - pos1;
+
+		result = (char *) g_malloc(len + 1);
+		if (result != NULL && (len = mio_read(File.mio, result, 1, len)) > 0)
 		{
-			result[pos2-pos1] = '\0';
+			result[len] = '\0';
 			arglist = getArglistFromStr(result, tokenName);
 		}
 		g_free(result);