[tlbuild] How to properly regenerate configure files?

[Mojca Miklavec]

Hi,

I need a patch for gregorio for the TeX Live package in MacPorts (TL
2016 doesn't compile with an old version of clang that's shipped on OS
X 10.7), but I don't know how to regenerate the configure file.

This is the patch that's required:
   https://github.com/gregorio-project/gregorio/pull/1186
Can someone please help me to get a modified configure file?

I tried to patch
    texk/gregorio/gregorio-src/configure.ac
but I guess I would have to modify
    texk/gregorio/configure.ac
instead?

The two files differ quite substantially though and I wonder whether
they would perhaps have to be synced (if the top level one is meant to
replace the original one).

I tried to run "autoreconf" inside texk/gregorio and the configure
file changed, but it didn't contain the required changes. The only
difference was

-#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
+#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))

at a number of places (plus some other minor changes).

Thank you,
    Mojca