parse: always initialize line pointer

Upon initializing the parser context, we do not currently initialize the
current line, line length and line number. Do so in order to make the
interface easier to use and more obvious for future consumers of the
parsing API.

src/parse.c

@@ -16,6 +16,9 @@ int git_parse_ctx_init(git_parse_ctx *ctx, const char *content, size_t content_l
 	ctx->content_len = content_len;
 	ctx->remain = ctx->content;
 	ctx->remain_len = ctx->content_len;
+	ctx->line = ctx->remain;
+	ctx->line_len = git__linenlen(ctx->line, ctx->remain_len);
+	ctx->line_num = 1;
 
 	return 0;
 }

src/patch_parse.c

@@ -613,10 +613,7 @@ static int parse_patch_header(
 {
 	int error = 0;
 
-	for (ctx->parse_ctx.line = ctx->parse_ctx.remain;
-		ctx->parse_ctx.remain_len > 0;
-		git_parse_advance_line(&ctx->parse_ctx)) {
-
+	for (; ctx->parse_ctx.remain_len > 0; git_parse_advance_line(&ctx->parse_ctx)) {
 		/* This line is too short to be a patch header. */
 		if (ctx->parse_ctx.line_len < 6)
 			continue;