Ilias Tsitsimpis authored Mar 01, 2020 and Marge Bot committed Mar 02, 2020

Do not define hs_atomicread64() and hs_atomicwrite64() on machines where
WORD_SIZE_IN_BITS is less than 64, just like we do with the rest of the atomic
functions which work on 64-bit values.

Without this, compilation fails on MIPSel and PowerPC with the following error:

/usr/bin/ld: /<<PKGBUILDDIR>>/libraries/ghc-prim/dist-install/build/libHSghc-prim-0.5.3_p.a(atomic.p_o): in function `hs_atomicread64':
atomic.c:(.text.hs_atomicread64+0x8): undefined reference to `__sync_add_and_fetch_8'
/usr/bin/ld: /<<PKGBUILDDIR>>/libraries/ghc-prim/dist-install/build/libHSghc-prim-0.5.3_p.a(atomic.p_o): in function `hs_atomicwrite64':
atomic.c:(.text.hs_atomicwrite64+0x38): undefined reference to `__sync_bool_compare_and_swap_8'

Fixes #17886.