Migrate to using musl libc sscanf to improve performance. Keep the existing JS vfscanf for Emscripten FS compatibility, and add the musl-specific version to be used when called from sscanf and vsscanf.
Skip the sscanf-requiring tests in suites that don't link to musl libc.
Migrate to using musl libc sprintf family to gain compiled asm.js performance. Keep a copy of handwritten vfprintf and fprintf around to be compatible with the Emscripten filesystem IO library. Also migrate frexp which sprintf depends on to musl libc.
Skip sprintf-accessing tests on s_ suites that require linking to libc.
Improve error messages from SAFE_HEAP_ACCESS function.
Fix test_cases to run after previous musl changes.
Migrate snprintf to musl. Move the most common sprintf-related code to libc instead of libcextra to avoid pulling libcextra in on common runs.
Disable testing the x86 triple i386-pc-linux-gnu in asm2.test_cube2hash, that triple is now deprecated.
Fix test test_sscanf to be spec-conformant in the treatment of scanf format specifiers. According to the standard, %255c matches exactly 255 characters, while %255s matches up to 255 characters.
Remove leftover scanf and printf stubs from library.js
Test s_0_0.test_dlfcn_stacks needs ta2.
Update the simd.js

It bases on
https://github.com/johnmccutchan/ecmascript_simd/blob/b5dce3a7039a6d38cb7922f526cdb49a69f01dc5/src/ecmascript_simd.js

API changes:
* Added shiftLeft, shiftRightLogical, shiftRightArithmetic on int32x4.
* Added equals, greaterThan, and lessThan that operate on int32x4.
* Add bit operations (and, or, xor, and not) that operate directly on float32x4.
* Moved constructors into SIMD module.
* Remove use of "new float32x4" and "new uint32x4"
Move float32x4 and int32x4 constructors into SIMD module.
fix asm2.test_memorygrowth
fix slow2asm.test_dlfcn_self
use response files for everything and remove unnecessary settings
add myself to authors
add test for building shared and static libraries with cmake
fix case of exceptions whitelist being empty
glTex[Sub]Image* should not throw an exception, but should cause a GL_INVALID_ENUM error on unrecognized formats or types