package/libcgroup: fix build with BR2_TIME_BITS_64

package/libcgroup: fix build with BR2_TIME_BITS_64

Do not remove _FILE_OFFSET_BITS=64 from CFLAGS and CPPFLAGS to avoid the
following build failure with BR2_TIME_BITS_64 raised since commit
3c427c64726560ea1743282a3fdb78f5b28692eb:

In file included from /home/fabrice/buildroot/output/host/mips-buildroot-linux-gnu/sysroot/usr/include/features.h:394,
                 from ../include/libcgroup/error.h:9,
                 from ../include/libcgroup.h:21,
                 from log.c:15:
/home/fabrice/buildroot/output/host/mips-buildroot-linux-gnu/sysroot/usr/include/features-time64.h:26:5: error: #error "_TIME_BITS=64 is allowed only with _FILE_OFFSET_BITS=64"
   26 | #   error "_TIME_BITS=64 is allowed only with _FILE_OFFSET_BITS=64"
      |     ^~~~~

Indeed, this LFS workaround is there since the addition of the package
in commit ff7191c12e88b044848f6655f7015335235bdc7a and is only needed to
fix a build failure with the old codesourcery-arm toolchain from 2014
which uses glibc < 2.23. as glibc 2.23 was released in February 2016:
https://sourceware.org/glibc/wiki/Release/2.23, drop this workaround as
already done for libselinux in commit
c1fa9bc2f7a4e5481edf4fce5c03dd45862fe72c. A follow-up patch will also
drop codesourcery-arm toolchain.

Fixes: 3c427c64726560ea1743282a3fdb78f5b28692eb
 - No autobuilder failures (yet)

Signed-off-by: Fabrice Fontaine <[email protected]>
Signed-off-by: Peter Korsgaard <[email protected]>