dsputil: Move APE-specific bits into apedsp

libavcodec/apedec.c

libavcodec/apedsp.h

libavcodec/arm/Makefile

libavcodec/arm/apedsp_init_arm.c

libavcodec/arm/apedsp_neon.S

libavcodec/arm/dsputil_init_neon.c

libavcodec/arm/int_neon.S

libavcodec/dsputil.c

libavcodec/dsputil.h

libavcodec/ppc/Makefile

libavcodec/ppc/apedsp_altivec.c

libavcodec/ppc/int_altivec.c

libavcodec/x86/Makefile

libavcodec/x86/apedsp.asm

libavcodec/x86/apedsp_init.c

libavcodec/x86/dsputil.asm

libavcodec/x86/dsputil_init.c