OpenBLAS: Build failure on circle-ci: f951: Error: bad value (skylake-avx512) for -march= switch

Hi

Release 0.3.4 fails to build on Linux (on our CI), with gcc5 and gcc6. (related issue, https://github.com/Linuxbrew/homebrew-core/pull/10455).

CPU: 36-core 64-bit skylake Kernel: Linux 4.4.0-139-generic x86_64 GNU/Linux OS: Ubuntu 16.04.5 LTS (xenial) Host glibc: 2.23

Last 150 lines from /home/linuxbrew/.cache/Homebrew/Logs/openblas/01.make:
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o spotrf2.o spotrf2.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgetrf2.o sgetrf2.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgbbrd.o sgbbrd.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgbcon.o sgbcon.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgbequ.o sgbequ.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgbrfs.o sgbrfs.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgbsv.o sgbsv.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgbsvx.o sgbsvx.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgbtf2.o sgbtf2.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgbtrf.o sgbtrf.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgbtrs.o sgbtrs.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgebak.o sgebak.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgebal.o sgebal.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgebd2.o sgebd2.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgebrd.o sgebrd.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgecon.o sgecon.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgeequ.o sgeequ.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgees.o sgees.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgeesx.o sgeesx.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgeev.o sgeev.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgeevx.o sgeevx.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgehd2.o sgehd2.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgehrd.o sgehrd.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgelq2.o sgelq2.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgelqf.o sgelqf.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgels.o sgels.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgelsd.o sgelsd.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgelss.o sgelss.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgelsy.o sgelsy.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgeql2.o sgeql2.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgeqlf.o sgeqlf.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgeqp3.o sgeqp3.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgeqr2.o sgeqr2.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgeqr2p.o sgeqr2p.f
gfortran -O2 -Wall -m64 -fopenmp -fPIC -march=skylake-avx512 -c -o sgeqrf.o sgeqrf.f
f951: Error: bad value (skylake-avx512) for -march= switch
Makefile:602: recipe for target 'sbdsvdx.o' failed
make[2]: *** [sbdsvdx.o] Error 1
make[2]: *** Waiting for unfinished jobs....
f951: Error: bad value (skylake-avx512) for -march= switch
Makefile:602: recipe for target 'sgbcon.o' failed
make[2]: *** [sgbcon.o] Error 1
f951: Error: bad value (skylake-avx512) for -march= switch
Makefile:602: recipe for target 'spotrf2.o' failed
make[2]: *** [spotrf2.o] Error 1
f951: Error: bad value (skylake-avx512) for -march= switch
f951: Error: bad value (skylake-avx512) for -march= switch
Makefile:602: recipe for target 'sgbequ.o' failed
make[2]: *** [sgbequ.o] Error 1
Makefile:602: recipe for target 'sgbsv.o' failed
make[2]: *** [sgbsv.o] Error 1
f951: Error: bad value (skylake-avx512) for -march= switch
f951: Error: bad value (skylake-avx512) for -march= switch
Makefile:602: recipe for target 'sgeequ.o' failed
make[2]: *** [sgeequ.o] Error 1
Makefile:602: recipe for target 'sgeevx.o' failed
make[2]: *** [sgeevx.o] Error 1
f951: Error: bad value (skylake-avx512) for -march= switch
Makefile:602: recipe for target 'sgbrfs.o' failed
make[2]: *** [sgbrfs.o] Error 1
f951: Error: bad value (skylake-avx512) for -march= switch
Makefile:602: recipe for target 'sgbbrd.o' failed
make[2]: *** [sgbbrd.o] Error 1
f951: Error: bad value (skylake-avx512) for -march= switch

Previous openblas versions were fine.