Add androideabi toolchain rake task (Build mruby with Android NDK)
Generate mrbtest.a file for sparete from driver.o
Fixed failure
Modify handling of integer literal.

Do not assume that significand of `double` is larger than `mrb_int`.
Prevent overflow of `Fixnum#to_s`.
Fix potential bug about Hash.
Restore arena in `String#split`.
removed declarations of undefined functions
Merge pull request #820 from cremno/unused-stuff

Remove declarations of undefined functions
Merge pull request #817 from masamitsu-murase/restore_arena_in_string_split

Restore arena in `String#split`.
Merge pull request #816 from masamitsu-murase/modify_potential_error_of_hash

Fix potential bug about Hash.
Merge pull request #815 from masamitsu-murase/modify_handling_of_large_fixnum

Modify handling of large fixnum
Merge pull request #812 from shtirlic/androideabi

Add androideabi toolchain rake task (Build mruby with Android NDK)
Merge pull request #813 from masuidrive/generate_mrbtest_a

Generate mrbtest.a file for sparete from driver.o