cpuid: fix PIC compilation with 32-bits gcc, which uses ebx
c_examples: fix format warning by casting size_t to ulong
Compile shared objects with hidden visibility
nolibc: disable stack protector, as it enabled by default on Ubuntu
windows_examples: skip compilation if no Windows compiler is found
syslinux-mbr: fix Makefile to be able to run clang
syslinux-mbr: add "check" target to Makefile to check the sha1sum of compiled MBR files