Cannot build for iOS arm64

What steps will reproduce the problem?
1. Edit iosbuild.sh, adding arm64 arch
2. Edit iosbuild.sh, change host to aarch64-apple-darwin

What is the expected output? 
Successful build

What do you see instead?
dec_neon.c:110:17: error: unknown register name 'q0' in asm
    : "memory", QRegs
                ^
dec_neon.c:21:15: note: expanded from macro 'QRegs'
#define QRegs "q0", "q1", "q2", "q3",                                          \
              ^
dec_neon.c:136:17: error: unknown register name 'r4' in asm
    : "memory", "r4", "r5", "r6", QRegs
                ^
dec_neon.c:304:17: error: unknown register name 'q0' in asm
    : "memory", "q0", "q1", "q2", "q8", "q9", "q10", "q11"  /* clobbered */
                ^
dec_neon.c:342:17: error: unknown register name 'q0' in asm
    : "memory", "q0", "q1", "q2", "q3"  /* clobbered */
                ^
dec_neon.c:408:17: error: unknown register name 'q0' in asm
    : "memory", "q0", "q1", "q2", "q3",
                ^
5 errors generated.

What version of the product are you using? On what operating system?
libwebp 0.4.0
XCode 5.0.2
Mac OS 10.8.5

Please provide any additional information below.
Perhaps the code needs to be changed to support arm64 registers?

Original issue reported on code.google.com by versae...@gmail.com on 2 Jan 2014 at 5:57

teasame / webp

Cannot build for iOS arm64 #182