Merge tag 'upstream/1.5.1'

Upstream version 1.5.1

Conflicts:
	BUILDING.md
	CMakeLists.txt
	ChangeLog.md
	Makefile.am
	Makefile.in
	configure
	configure.ac
	jdarith.c
	jdmaster.c
	jdphuff.c
	jpegint.h
	simd/Makefile.am
	simd/Makefile.in
	simd/jsimd_arm64_neon.S
	simd/jsimd_mips.c
	simd/jsimd_powerpc.c