build-openmp: Build the OpenMP library on all architectures

Since a356782426f5bf54a00570e1f925345e5fda7b2e in llvm-project,
OpenMP can be built for mingw/aarch64, since
fb947c358661b3bd3d5e1fa776ec74cc0f308854 it should work correctly
in all currently tested cases, and since
97958c9bb83cec44b6ce13e732b53de0171a5d43 it can be built for
mingw/armv7.

build-openmp.sh

@@ -72,15 +72,9 @@ fi
 for arch in $ARCHS; do
     CMAKEFLAGS=""
     case $arch in
-    i686)
-        ;;
     x86_64)
         CMAKEFLAGS="$CMAKEFLAGS -DLIBOMP_ASMFLAGS=-m64"
         ;;
-    *)
-        # Not supported
-        continue
-        ;;
     esac
 
     [ -z "$CLEAN" ] || rm -rf build-$arch