package/libgcrypt: fix build on ARM without NEON

package/libgcrypt: fix build on ARM without NEON

Backport an upstream-pending patch to fix build on ARM without NEON:

    libtool: link: /home/ymorin/dev/buildroot/O/host/bin/arm-linux-gcc -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -fvisibility=hidden -fno-delete-null-pointer-checks -Wall -o mpicalc mpicalc-mpicalc.o  ./.libs/libgcrypt.so -lgpg-error -Wl,-rpath -Wl,/home/ymorin/dev/buildroot/O/build/libgcrypt-1.9.0/src/.libs
    /home/ymorin/dev/buildroot/O/host/opt/ext-toolchain/bin/../lib/gcc/arm-buildroot-linux-uclibcgnueabi/5.5.0/../../../../arm-buildroot-linux-uclibcgnueabi/bin/ld: ./.libs/libgcrypt.so: undefined reference to `_gcry_sha512_transform_armv7_neon'

Fixes:
    http://autobuild.buildroot.org/results/9fe1439811f89917041cfb2d40ad2b8015a6fc28/

Reported-by: montjoie on IRC
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>