aarch64: replace alias vector mov with orr

Xcode 5 and 5.1 both do not support the alias.
aarch64: append optional left shift to certain movi variants

Xcode 5 and 5.1 complain over the missing shift although it's optional
according to the reference manual.
aarch64: replace alias uxtl with ushll

Clang from Xcode 5 does not support uxtl.
aarch64: fix bsl|saddl2? for Xcode5

Clang from Xcode5 supports bsl/saddl2? only in an unofficial assembler
syntax. To avoid breakage with later versions or different assembler
gas-preprocessor.pl checks for the environment variable GASPP_FIX_XCODE5
before changing these instructions to the non-standard syntax.
arm: rewrite .func directive as .thumb_func for thumb

Makes sure all local function symbols are declared as .thumb_func
even if they are not directly called. fft4|65536_neon in
libavcodec/arm/fft_neon.S are only accessed through saved offset in
a table for example. Fixes fate-mdct-4 tests in libav on iOS.
Check the matched conditions in regexps that match branches

This avoids interpreting instructions such as e.g. bic as
a branch with the condition 'ic'.