[Issue] defforeign test fails for armhf

[mmurooka]

While debugging euslisp/jskeus#538, in which travis fails only for armhf: https://travis-ci.org/euslisp/jskeus/builds/583683006, I found that float-type argument and return value are not passed correctly only for armhf in defforeign. (If argument is passed as array, this problem does not occur.)

To treat this problem, this PR adds a simple defforeign test and confirms that a test fails for armhf: https://travis-ci.org/mmurooka/EusLisp/builds/584646890
Difficult to solve for me, so any suggestions are welcome.

travis test example of NOT armhf case (success):
https://travis-ci.org/mmurooka/EusLisp/jobs/584646891

TEST-NAME: test-defforeign
  now testing...
�[32mstart testing [test-defforeign]
�[0m// v1: 1
// v2: 2.500000
test1: 3.5
// v[0]: 1.000000
// v[1]: 2.500000
test2: 3.5
ALL RESULTS:
  TEST-NUM: 1
    PASSED:   1
    FAILURE:  0

travis test example of armhf case (failure):
https://travis-ci.org/mmurooka/EusLisp/jobs/584646897

TEST-NAME: test-defforeign
  now testing...
�[32mstart testing [test-defforeign]
�[0m// v1: 1
// v2: 71305339651524827816686256128.000000
test1: 0.0
�[31m[ERROR] test (= test1-result 3.5) failed ... ( ^[0mmstart testing [test-defforeign]
ed on dc9274a57492(Fri Sep 13 15:34:25 UTC 2019)^[0m鐃���鐃緒申��鐃緒申��鐃緒申��鐃緒申��鐃緒申��鐃緒申��鐃緒申��鐃緒申��鐃緒申��).�[0m
// v[0]: 1.000000
// v[1]: 2.500000
test2: 2.5
�[31m[ERROR] test (= test2-result 3.5) failed ... ( UTC 2019)^[0m鐃���鐃緒申��鐃緒申��鐃緒申��鐃緒申��鐃緒申��鐃緒申��鐃緒申��鐃緒申��鐃緒申��).^[0m
art testing [test-defforeign]
ed on dc9274a57492(Fri Sep 13 15:34:25 ).�[0m
ALL RESULTS:
  TEST-NUM: 1
    PASSED:   0
�[31m    FAILURE:  1