parse: remove use of variadic macros which are not C89 compliant

The macro `git_parse_error` is implemented in a variadic way so
that it's possible to pass printf-style parameters.
Unfortunately, variadic macros are not defined by C89 and thus we
cannot use that functionality. But as we have implemented
`git_error_vset` in the previous commit, we can now just use that
instead.

Convert `git_parse_error` to a variadic function and use
`git_error_vset` to fix the compliance violation. While at it,
move the function to "patch_parse.c".

src/parse.h

@@ -28,9 +28,6 @@ typedef struct {
 int git_parse_ctx_init(git_parse_ctx *ctx, const char *content, size_t content_len);
 void git_parse_ctx_clear(git_parse_ctx *ctx);
 
-#define git_parse_err(...) \
-	( git_error_set(GIT_ERROR_PATCH, __VA_ARGS__), -1 )
-
 #define git_parse_ctx_contains_s(ctx, str) \
 	git_parse_ctx_contains(ctx, str, sizeof(str) - 1)
 

src/patch_parse.c

@@ -33,6 +33,18 @@ typedef struct {
 	char *old_prefix, *new_prefix;
 } git_patch_parsed;
 
+static int git_parse_err(const char *fmt, ...) GIT_FORMAT_PRINTF(1, 2);
+static int git_parse_err(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	git_error_vset(GIT_ERROR_PATCH, fmt, ap);
+	va_end(ap);
+
+	return -1;
+}
+
 static size_t header_path_len(git_patch_parse_ctx *ctx)
 {
 	bool inquote = 0;