Fix memory leak when using select_every filter
filters: fix sizeof mismatch
arm: do not append CFLAGS to ASFLAGS
arm: set .arch/.fpu from asm.S
arm: move instructions after '.rept' to separate line

The gas manual states "Repeat the sequence of lines between the .rept
directive and the next .endr directive ...". GNU as seems to support
instructions on the same line as .rept anyway but the integrated
assembler in llvm trunk (to be released 3.5 in August 2014) does not.
arm/ppc: use $CC as default assembler
arm: check if the assembler supports the '.func' directive

The integrated assembler in llvm trunk (to be released as 3.5) is
otherwise capable enough to assemble the arm asm correctly.
checkasm: add memory clobber to read_time inline asm

The memory acts as compiler barrier preventing aggressive reordering
of read_time calls. gcc 4.8 reorders some of initial read_time calls
after the second when targeting arm.
arm: do not use aligned stores in mc_weight_w4_*neon

mc_weight_w4_*neon is also used for width 2 which does not guarantee
4-byte aligned destination. Fixes crashes caused by random memory
corruption.
arm: use long multiplication in mc_weight_w*_neon

9-19% faster on a cortex-a9.
checkasm: test zigzag_sub_8x8_{frame,field}
aarch64: initial build support
aarch64: add armv8 and neon cpu flags and test them
aarch64: add utility functions for asm
aarch64: pixel metrics NEON asm

Ported from the ARM NEON asm.
aarch64: quantization and level-run NEON asm

Ported from the ARM NEON asm.
aarch64: transform and zigzag NEON asm

Ported from the ARM NEON asm.
aarch64: motion compensation NEON asm

Ported from the ARM NEON asm.
aarch64: intra predition NEON asm

Ported from the ARM NEON asm.
aarch64: deblocking NEON asm

Deblock chroma/luma are based on libav's h264 aarch64 NEON deblocking
filter which was ported by me from the existing ARM NEON asm. No
additional persons to ask for a relicense.