run avx512 builds on Linux machines that support it

Change-Id: Iddd79c1e26e627f6c1244a3525e538cc91adf68c
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/197828
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
diff --git a/build/clang.avx512 b/build/clang.avx512
index 78664e2..cb1225e 100644
--- a/build/clang.avx512
+++ b/build/clang.avx512
@@ -2,4 +2,4 @@
 extra_cflags = -march=skylake-avx512
 include build/clang
 
-disabled = (uname | grep -qv Darwin || sysctl machdep.cpu.leaf7_features | grep -qv AVX512F)
+disabled = (uname | grep -q Darwin && sysctl machdep.cpu.leaf7_features | grep -qv AVX512F || grep flags /proc/cpuinfo | grep -vq avx512f)