use llvm8 for crystal
Crystal supports and recommends llvm8 according https://crystal-lang.org/install/from_sources/
It builds with llvm8 on x86_64 but fails on aarch64:
...
gcc: error: N-amedT-uple40that5832S-tring41.o: No such file or directory
gcc: error: S-tring5858F-orma-085b5dc881ab7de10ca237a67e98084f.o: No such file or directory
gcc: error: T-uple40H-ash40S-tring4432I-nt324141.o: No such file or directory
gcc: error: H-ash40S-tring4432F-loat6441.o: No such file or directory
gcc: error: P-ointer40H-ash5858E-ntry40S-tring4432F-loat644141.o: No such file or directory
gcc: error: H-ash5858E-ntry40S-tring4432F-loat6441.o: No such file or directory
gcc: error: S-tring5858F-orma-d26233462d11ec2bbb91298642335fcf.o: No such file or directory
gcc: error: T-uple40H-ash40S-tring4432F-loat644141.o: No such file or directory
gcc: error: S-tring5858F-orma-959486422997d82e4b2df36180c33548.o: No such file or directory
gcc: error: H-T-T-P-5858C-lient5858R-esponse.o: No such file or directory
gcc: error: E-mptyI-O-.o: No such file or directory
gcc: error: O-penS-S-L-5858S-S-L-5858S-ocket5858C-lient.o: No such file or directory
gcc: error: U-D-P-S-ocket.o: No such file or directory
gcc: error: I-P-S-ocket.o: No such file or directory
gcc: error: P-ointer40L-ibC-rypto5858B-io41.o: No such file or directory
gcc: error: L-ibC-rypto5858B-io.o: No such file or directory
gcc: error: P-ointer40L-ibC-r-3d955a7e9c76bf2d46cf2ef3aa00d05c.o: No such file or directory
gcc: error: L-ibC-rypto5858E-V-P-_M-D-_C-T-X-_S-truct.o: No such file or directory
gcc: error: O-penS-S-L-5858S-S-L-5858S-ocket.o: No such file or directory
gcc: error: I-O-5858S-ized.o: No such file or directory
gcc: error: H-T-T-P-5858C-lient.o: No such file or directory
gcc: error: S-pec5858B-eE-xpe-e8d4265fbb8943267419a4d6be62c8cb.o: No such file or directory
gcc: error: A-rray40P-roc40H-T-T-P-5858R-equest4432N-il4141.o: No such file or directory
gcc: error: P-ointer40P-roc40H-T-T-P-5858R-equest4432N-il4141.o: No such file or directory
gcc: error: T-estC-lient.o: No such file or directory
gcc: error: A-rray40H-T-T-P-5858S-tatus41.o: No such file or directory
gcc: error: P-ointer40H-T-T-P-5858S-tatus41.o: No such file or directory
gcc: error: 47home47ncopa47ap-9bee3798861a2b36df36a9a1299fc3d2.o: No such file or directory
gcc: error: C-hannel40S-ymbol41.o: No such file or directory
gcc: error: D-eque40C-hannel5858S-ender40S-ymbol4141.o: No such file or directory
gcc: error: P-ointer40C-hannel5858S-ender40S-ymbol4141.o: No such file or directory
gcc: error: D-eque40C-hannel5858R-eceiver40S-ymbol4141.o: No such file or directory
gcc: error: P-ointer40C-hannel5858R-eceiver40S-ymbol4141.o: No such file or directory
gcc: error: D-eque40S-ymbol41.o: No such file or directory
gcc: error: I-O-5858L-ineI-terator40I-4432A-4432N-41.o: No such file or directory
gcc: error: I-O-5858L-ineI-te-2bbac0f896af39065c5146eb11c4bcdc.o: No such file or directory
gcc: error: I-O-5858L-ineI-te-cb8f91cbbce440db16f9b72c4ba16321.o: No such file or directory
gcc: error: I-O-5858C-harI-terator40I-41.o: No such file or directory
gcc: error: I-O-5858C-harI-terator40S-impleI-O-M-emory41.o: No such file or directory
gcc: error: I-O-5858B-yteI-terator40I-41.o: No such file or directory
gcc: error: I-O-5858B-yteI-terator40S-impleI-O-M-emory41.o: No such file or directory
gcc: error: S-tring5858F-orma-f67b8d4c7ce3c0910c4f1f06722d6071.o: No such file or directory
gcc: error: T-uple40S-tring4432I-nt324432F-loat6441.o: No such file or directory
gcc: error: O-A-uth25858A-ccessT-oken5858M-ac.o: No such file or directory
gcc: error: O-A-uth25858A-ccessT-oken43.o: No such file or directory
gcc: error: S-pec5858E-qualE--095d6df8d7a80d9983e647bde0e23030.o: No such file or directory
Error: execution of command failed with code: 1: `gcc "${@}" -o '/home/ncopa/aports/community/crystal/src/crystal-0.31.1/.build/all_spec' -Wl,--as-needed -rdynamic -lreadline -lgmp -lxml2 -lyaml -lz `command -v pkg-config > /de
v/null && pkg-config --libs --silence-errors libssl || printf %s '-lssl -lcrypto'` `command -v pkg-config > /dev/null && pkg-config --libs --silence-errors libcrypto || printf %s '-lcrypto'` /home/ncopa/aports/community/crystal/s
rc/crystal-0.31.1/src/llvm/ext/llvm_ext.o `/usr/bin/llvm8-config --libs --system-libs --ldflags 2> /dev/null` -lstdc++ -lpcre -lm /usr/lib/libgc.a -lpthread /home/ncopa/aports/community/crystal/src/crystal-0.31.1/src/ext/libcryst
al.a -levent -lrt -L/usr/lib -L/usr/local/lib`
make: *** [Makefile:120: .build/all_spec] Error 1
>>> ERROR: crystal: check failed