Add #define _GNU_SOURCE so that transaction.go can reference C.RTLD_NEXT

[astudentofblake]

RTLD_NEXT is inside a #ifdef __USE_GNU block in dlfcn.h, which causes the build to fail

This in AlmaLinux release 8.10 (Cerulean Leopard), binary compatible with RHEL

fixes #34

[3v1n0]

Maybe this should be only in #ifdef __linux__ and other UNIX systems using glibc?

[3v1n0]

Otherwise you can define _GNU_SOURCE for all, then you add an #ifndef RTLD_NEXT that sets it to 0 if unset? I'm not aware of platforms where that is not set, but it's safer to go this way.

[msteinert]

Or #if defined(__GLIBC__) maybe?

[astudentofblake]

Sorry for the delayed response

Not obvious what the best solution is here,
GLIBC is defined in features.h, which I could include to test the define, however features.h sets defines based on _GNU_SOURCE, so its not really correct.

I'll update the request with the second suggestion, define _GNU_SOURCE and add the ifndef, from the include file: -

define RTLD_NEXT ((void *) -1l)

I'm assuming this is what you mean (rather than set to zero).

[astudentofblake]

sorry, the define text being really large is a copy-paste error.

[szaydel]

I ran into this issue recently as well. May I suggest placing these changes into transaction_linux.go, and perhaps use #cgo CFLAGS: -D_GNU_SOURCE, which seems to be the preferred method.