gcc -Os -fomit-frame-pointer -pipe -x none minitests.o libvacall.a -Wl,--as-needed -o minitests
  /usr/lib/gcc/armv6-alpine-linux-musleabihf/6.4.0/../../../../armv6-alpine-linux-musleabihf/bin/ld: libvacall.a(vacall.o): relocation R_ARM_MOVW_ABS_NC against `vacall_function' can not be used when making a shared object; recompile with -fPIC
  libvacall.a: error adding symbols: Bad value
  collect2: error: ld returned 1 exit status
  make[1]: *** [Makefile:271: minitests] Error 1

  gcc -Os -fomit-frame-pointer -x none minitests.o libvacall.a -Wl,--as-needed -o minitests
  i586-alpine-linux-musl-g++ -Os -fomit-frame-pointer -x none minitests-c++.o libvacall.a -Wl,--as-needed -o minitests-c++
  ./minitests > minitests.out
  Segmentation fault
  make[1]: *** [Makefile:280: check] Error 139

Fails with (apparently due to new gcc toolchain):

gcc -E `if test false = true; then echo '-DASM_UNDERSCORE'; fi` ./vacall-arm.S | grep -v '^ *#line' | grep -v '^#' | sed -e 's,% ,%,g' -e 's,//,@,g' -e 's,\$,#,g' > vacall-arm.s
gcc -x none -c vacall-arm.s
vacall-arm.s: Assembler messages:
vacall-arm.s:3: Warning: ignoring attempt to redefine built-in register 'sl'
vacall-arm.s:4: Warning: ignoring attempt to redefine built-in register 'fp'
vacall-arm.s:5: Warning: ignoring attempt to redefine built-in register 'ip'
vacall-arm.s:6: Warning: ignoring attempt to redefine built-in register 'sp'
vacall-arm.s:7: Warning: ignoring attempt to redefine built-in register 'lr'
vacall-arm.s:8: Warning: ignoring attempt to redefine built-in register 'pc'
vacall-arm.s:80: Error: selected processor does not support `ldfeqs f0,[sp,#20]' in ARM mode
vacall-arm.s:84: Error: selected processor does not support `ldfeqd f0,[sp,#20]' in ARM mode
Makefile:105: recipe for target 'vacall-arm.o' failed
make[1]: *** [vacall-arm.o] Error 1

See also:
https://wiki.debian.org/ArmEabiProblems (search for ffcall)

Since abuild v2.22.0, these are removed automatically unless 'libtool'
option has been specified.