Rules: Check for CROSS_COMPILE to be empty
Rules: Check for CROSS_COMPILE to be empty

In some case where CROSS is defined to be empty
we define CROSS_COMPILE ?= CROSS so at this point
it will be defined but will be empty so check
for the same

Signed-off-by: Khem Raj <729d64b6f67515e258459a5f6d20ec88b2caf8df@gmail.com>

kraj/uclibc-ng,brgl/uclibc-ng,ndmsystems/uClibc,foss-xtensa/uClibc,hjl-tools/uClibc,mephi42/uClibc,hwoarang/uClibc,waweber/uclibc-clang,groundwater/uClibc,skristiansson/uClibc-or1k,foss-xtensa/uClibc,atgreen/uClibc-moxie,kraj/uclibc-ng,mephi42/uClibc,atgreen/uClibc-moxie,groundwater/uClibc,hwoarang/uClibc,wbx-github/uclibc-ng,hwoarang/uClibc,ffainelli/uClibc,mephi42/uClibc,groundwater/uClibc,kraj/uClibc,brgl/uclibc-ng,groundwater/uClibc,kraj/uclibc-ng,czankel/xtensa-uclibc,hjl-tools/uClibc,majek/uclibc-vx32,majek/uclibc-vx32,mephi42/uClibc,hwoarang/uClibc,ndmsystems/uClibc,hjl-tools/uClibc,brgl/uclibc-ng,skristiansson/uClibc-or1k,foss-xtensa/uClibc,ddcc/klee-uclibc-0.9.33.2,groundwater/uClibc,atgreen/uClibc-moxie,kraj/uClibc,foss-for-synopsys-dwc-arc-processors/uClibc,waweber/uclibc-clang,ddcc/klee-uclibc-0.9.33.2,foss-for-synopsys-dwc-arc-processors/uClibc,hjl-tools/uClibc,ffainelli/uClibc,foss-for-synopsys-dwc-arc-processors/uClibc,ddcc/klee-uclibc-0.9.33.2,kraj/uclibc-ng,waweber/uclibc-clang,foss-xtensa/uClibc,foss-for-synopsys-dwc-arc-processors/uClibc,ffainelli/uClibc,ddcc/klee-uclibc-0.9.33.2,hjl-tools/uClibc,ffainelli/uClibc,czankel/xtensa-uclibc,wbx-github/uclibc-ng,kraj/uClibc,wbx-github/uclibc-ng,majek/uclibc-vx32,ndmsystems/uClibc,atgreen/uClibc-moxie,ndmsystems/uClibc,wbx-github/uclibc-ng,waweber/uclibc-clang,czankel/xtensa-uclibc,kraj/uClibc,czankel/xtensa-uclibc,brgl/uclibc-ng,skristiansson/uClibc-or1k,ffainelli/uClibc,majek/uclibc-vx32,skristiansson/uClibc-or1k