Disable emcc sanity checks for child processes to remove sleep hack

[aheejin]

TODO: Disable emcc sanity checks for child processes in emscripten and remove this hack. Looks like some related work is underway emscripten-core/emscripten#6124.

waterfall/src/build.py

Lines 1135 to 1153 in 53ed3e7

	# FIXME HACK emcc does sanity check by comparing mtime of the sanity file
	# with that of emscripten config file. The sanity check process in
	# emscripten thinks current cache is invalid when 'sanity file's mtime <=
	# config file's mtime'. embuilder launches emcc for each of system library
	# we need to build, and each of those emcc process in turn launches several
	# more emcc processes for each of .c source file included in the library.
	# Each of these emcc processes runs its own sanity check, which is
	# unnecessary anyway, and we are planning to fix it. But this is also
	# causing problems for Mac and Windows build in waterfall. The first emcc
	# process sees the configuration file has changed, deletes cache, and
	# rewrites the sanity file. Then, Mac OS X and Windows' timestamps for
	# mtime only have 1~2 seconds resolution, which makes it possible that
	# other emcc processes launched later by the initial emcc process again
	# think the cache is invalid and delete the cache again, which would then
	# contain half-built libraries, if less than 1 seconds has elapsed after
	# the first deletion. So here we make sure that enough time has elapsed
	# between configuration file writing and sanity checking, so that it would
	# temporarily work on Mac and Windows.
	time.sleep(3)

[dschuff]

Closing this as obsolete, and because we are moving the code (see #698). If there is an issue with the build scripts, please file an issue against EMSDK