mingw: allow for longer paths in parse_interpreter()

As reported in https://github.com/newren/git-filter-repo/pull/225, it
looks like 99 bytes is not really sufficient to represent e.g. the full
path to Python when installed via Windows Store (and this path is used
in the hasb bang line when installing scripts via `pip`).

Let's increase it to what is probably the maximum sensible path size:
MAX_PATH. This makes `parse_interpreter()` in line with what
`lookup_prog()` handles.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Vilius Šumskas <vilius@sumskas.eu>

compat/mingw.c

@@ -1605,7 +1605,7 @@ static const char *quote_arg_msys2(const char *arg)
 
 static const char *parse_interpreter(const char *cmd)
 {
-	static char buf[100];
+	static char buf[MAX_PATH];
 	char *p, *opt;
 	ssize_t n; /* read() can return negative values */
 	int fd;