Revert special handling of Windows xNRM2 and enable C+intrinsics kernel for SSUM/DSUM

kernel/x86_64/KERNEL

@@ -259,12 +259,8 @@ SNRM2KERNEL = nrm2_sse.S
 endif
 
 ifndef DNRM2KERNEL
-ifeq ($(OSNAME),WINNT)
-DNRM2KERNEL = ../arm/nrm2.c
-else
 DNRM2KERNEL = nrm2.S
 endif
-endif
 
 ifndef QNRM2KERNEL
 QNRM2KERNEL = nrm2.S
@@ -275,12 +271,8 @@ CNRM2KERNEL = znrm2_sse.S
 endif
 
 ifndef ZNRM2KERNEL
-ifeq ($(OSNAME),WINNT)
-ZNRM2KERNEL = ../arm/znrm2.c
-else
 ZNRM2KERNEL = znrm2.S
 endif
-endif
 
 ifndef XNRM2KERNEL
 XNRM2KERNEL = znrm2.S
@@ -486,3 +478,6 @@ XTRSMKERNEL_RN	=  xtrsm_kernel_LT_1x1.S
 XTRSMKERNEL_RT	=  xtrsm_kernel_LT_1x1.S
 
 XGEMM3MKERNEL    =  xgemm3m_kernel_2x2.S
+
+SSUMKERNEL = ../arm/sum.c
+DSUMKERNEL = ../arm/sum.c