xtensa: add a stub user.h file
xtensa: add a stub user.h file

Xtensa only supports the ELF binary format, so the user.h file isn't
needed. However, it's included by other files, so provide a stub user.h.

Signed-off-by: Chris Zankel <711c73f64afdce07b7e38039a96d2224209e9a6c@zankel.net>

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