configure.ac: add AC_USE_SYSTEM_EXTENSIONS

[ffontaine]

uint and alphasort come from glibc, and with ancient versions thereof, they were guarded behind different sets of feature-test macros (see manpage for scandir() for example), which were not default back then.

In file included from iprdump.c:17:0:
iprlib.h:1866:2: error: unknown type name 'uint'
  uint supported_with_min_ucode_level;
  ^

iprlib.c: In function 'ipr_get_pci_slots':
iprlib.c:1999:48: error: 'alphasort' undeclared (first use in this function)
  num_slots = scandir(rootslot, &slotdir, NULL, alphasort);
                                                ^

Fix them by adding AC_USE_SYSTEM_EXTENSIONS in configure.ac

Fixes:

• http://autobuild.buildroot.org/results/41fde4aa06f7c025bb05aa594716643b9010358f

Signed-off-by: Fabrice Fontaine fontaine.fabrice@gmail.com Signed-off-by: Yann E. MORIN yann.morin.1998@free.fr

[yann-morin-1998]

Technically, the issue is not with gcc, but with glibc.

uint and alphasort come from glibc, and with ancient versions thereof, they were guarded behind different sets of feature-test macros (see manpage for scandir() for example), which were not default back then.

And for reference: the failing test-case was using glibc-2.18, while the feature-test for alphasort() changed with glibc-2.19.

[ffontaine]

Thanks Yann, I updated the PR accordingly