Don't gate reading of Makefile.conf

This was gated behind GOTOBLAS_MAKEFILE, which looks like it's intended
to stop the much more expensive run of `Makefile.prebuild` rather than
prevent reading the configuration. Moving this `endif` means that things
such as `dynamic_<X>.c` correctly get the architecture flags.

Makefile.system

@@ -283,6 +283,7 @@ GETARCH_FLAGS += -DHAVE_GAS=$(HAVE_GAS)
 
 # Generating Makefile.conf and config.h
 DUMMY := $(shell $(MAKE) -C $(TOPDIR) -f Makefile.prebuild CC="$(CC)" FC="$(FC)" HOSTCC="$(HOSTCC)" HOST_CFLAGS="$(GETARCH_FLAGS)" CFLAGS="$(CFLAGS)" BINARY=$(BINARY) USE_OPENMP=$(USE_OPENMP) DYNAMIC_ARCH=$(DYNAMIC_ARCH) TARGET_CORE=$(TARGET_CORE) ONLY_CBLAS=$(ONLY_CBLAS) TARGET=$(TARGET) all)
+endif
 
 ifndef TARGET_CORE
 include $(TOPDIR)/Makefile.conf
@@ -306,8 +307,6 @@ HAVE_FMA3=
 include $(TOPDIR)/Makefile_kernel.conf
 endif
 
-endif
-
 ifndef NUM_PARALLEL
 NUM_PARALLEL = 1
 endif