Add -march=skylake-avx512 to SkylakeX part of DYNAMIC_ARCH builds

Author: martin-frbg

kernel/Makefile

@@ -6,7 +6,11 @@ TOPDIR	= ..
 include $(TOPDIR)/Makefile.system
 
 ifdef TARGET_CORE
+ifeq ($(TARGET_CORE), SKYLAKEX)
+override CFLAGS += -DBUILD_KERNEL -DTABLE_NAME=gotoblas_$(TARGET_CORE) -march=skylake-avx512
+else
 override CFLAGS += -DBUILD_KERNEL -DTABLE_NAME=gotoblas_$(TARGET_CORE)
+endif
 BUILD_KERNEL = 1
 KDIR =
 TSUFFIX = _$(TARGET_CORE)