bug fix: the argument of '--sysroot' option should be followed '=' character.
bug fix: add new option '-mandroid' into CFLAGS and same options are applied into LDFLAGS.
refactoring
add a new feature to select the target architecture.
add a new feature to select the target Android platform.
more CFLAGS and LDFLAGS are specified automatically.
experimental MRB_INT16 added
add mrb_int overflow check for mrb_int
Add break to default case in switch statement
bug fix: fix "--sysroot" option and host platform detection.
Fix indentation in symbol.c
support 'Cygwin' as build platform.
bug fix: fix wrong method name.
Merge pull request #975 from crimsonwoods/modify_build_script

Improve Android platform support.
Merge pull request #1007 from kano4/pr-add-break

Add break to default case in switch statement
resolve conflict
add mrbgem: mrb-array-ext
update build_config.rb
rename method
Remove bit-fields. They doesn't reduce memory on major environments.