make FS.ErrnoError inherit from Error
move shader compile status check behind GL_DEBUG
expose setCanvasSize
Merge pull request #1526 from inolen/glcompileshader

don't check COMPILE_STATUS in glCompileShader by default
make find_bigfuncs work on ll and js
Merge pull request #1527 from inolen/setcanvassize

export setCanvasSize to Module object
Merge pull request #1511 from inolen/errnoerror

make FS.ErrnoError inherit from Error
Add compat headers, move some things to them.

This is groundwork for landing musl includes which remove
some of the deprecated functions or very old BSDisms.
Fix test runner process exit code to report the number of failing tests, like it did before.
convert gl emulation compilation errors to warnings and runtime errors
pick up function indexing that only happens in pre
simplify and automate GetProcAddress logic, and move it out of GL emulation
do not warn on gl emulation code if INCLUDE_FULL_LIBRARY is set, only error at runtime
generate separate function table wrappers for a single library function aliased with different signatures
warn on VERBOSE
allow overriding a gl function with the same name, and keep the original accessible through getProcAddress
Merge pull request #1532 from juj/fix_test_runner_returncode

Fix test runner returncode.
create FS.name_table at runtime, to reduce code size
Merge pull request #1529 from waywardmonkeys/compat-headers

Compat headers
clean up sv sockets for socket tests