darktable: work around omp bug w/ aarch64

Do not use OMP in the function process_lch_xtrans in src/iop/highlights.c
if the architecture is aarch64. Otherwise the build fails with:
src/iop/highlights.c:700:17: error: '*.LC2' not specified in enclosing 'parallel'

srcpkgs/darktable/patches/fix-omp-aarch64.patch

@@ -0,0 +1,18 @@
+--- src/iop/highlights.c	2019-10-20 14:39:07.000000000 +0200
++++ src/iop/highlights.c	2019-12-09 11:09:14.468776742 +0100
+@@ -625,12 +625,14 @@
+                                const dt_iop_roi_t *const roi_out, const float clip)
+ {
+   const uint8_t(*const xtrans)[6] = (const uint8_t(*const)[6])piece->pipe->dsc.xtrans;
+-
++/* fails for aarch64 with: highlights.c:700:17: error: '*.LC2' not specified in enclosing 'parallel' */
++#if !defined(__aarch64__)
+ #ifdef _OPENMP
+ #pragma omp parallel for default(none) \
+   dt_omp_firstprivate(clip, ivoid, ovoid, roi_in, roi_out, xtrans) \
+   schedule(dynamic)
+ #endif
++#endif
+   for(int j = 0; j < roi_out->height; j++)
+   {
+     float *out = (float *)ovoid + (size_t)roi_out->width * j;

srcpkgs/darktable/template

@@ -23,7 +23,3 @@ homepage="http://www.darktable.org/"
 changelog="https://github.com/darktable-org/darktable/releases"
 distfiles="https://github.com/darktable-org/darktable/releases/download/release-${version}/darktable-${version}.tar.xz"
 checksum=a518999c8458472edfc04577026ce5047d74553052af0f52d10ba8ce601b78f0
-
-case "$XBPS_TARGET_MACHINE" in
-	aarch64*) broken="https://build.voidlinux.org/builders/aarch64_builder/builds/22479/steps/shell_3/logs/stdio" ;;
-esac