ARM: can build with llvm, switch to EABI

	. bitcode fixes
	. switch to compiler-rt instead of netbsd libc functions
	  or libgcc for support functions for both x86 and arm
	. minor build fixes
	. allow  build with llvm without crossbuilding llvm itself
	. can now build minix/arm using llvm and eabi - without C++
	  support for now (hence crossbuilding llvm itself is turned off
	  for minix/arm)

Change-Id: If5c44ef766f5b4fc4394d4586ecc289927a0d6eb