Fix #1668: whiteSpace in _scanString should use only char codes as keys not chars and char codes.
Use the logging framework instead of print, to be consistent and as the logging framework prints out messages unbuffered which is more responsive on Windows.

Add debug logging facility to track waits on external processes when EM_BUILD_VERBOSE >= 3. This helps pinpointing if the build hangs on some tool dying/live/deadlocking, and where it might occur.

Implement process.pid on WindowsPopen replacement so that EM_BUILD_VERBOSE=3 works on it as well.
Don't do Popen workaround on Windows by default, since the cmdline -> call emcc.bat usage doesn't seem to need it, and it adversely affects the logging buffering that makes the compiler look unresponsive, since it will only print out compilation output messages at the very end of the whole run.
Merge pull request #1631 from juj/responsive_logging

Responsive logging
Merge pull request #1669 from ngld/fix-sscanf-whitespace

Fix #1668: whiteSpace in _scanString should use only char codes as keys
optimize getFastValue
fix debug printout
add slack to test_sdl_canvas_alpha
remove makeGetPos and part of noNeedFirst
fix getFastValue regression
hackish optimization for pre processing of heap inits, avoid pure numeric strings
optimize makeSignOp
add total time to html compiler phase
optimize parseLLVMString
intertyper profiler
 - made chdir use FS.chdir
 - changed direct references to FS.currentPath to use FS.cwd()
 - fixed mountpoint resolving in mount
 - added async FS.syncfs
 - added idbfs and nodefs
 - minor coding convention fixes
- updated several unistd tests to test against NODEFS
=== in isLocalVar
better check for when things need quoting