test opengl examples on linux

[yxnan]

Tested files:

1. examples/opengl-demo-ffi-lsp.txt (on Linux 32/64-bit (AMD) minimum version newLISP 10.7.0)
2. examples/opengl-demo-ffi.lsp (on Linux 32/64-bit (AMD) minimum version newLISP 10.7.0)
3. examples/opengl-demo.lsp (on Linux 32-bit (AMD) minimum version newLISP 10.7.5)

Fixed some typos.

[coveralls]

Coverage remained the same at 0.0% when pulling f85298c66593b4c5b6cdf0da4e19f343c877a47c on sakamitz:develop into 9eb8f27de842ebe96e8a6f8e631ffd3fa37d4611 on kosh04:develop.

[codecov-io]

Codecov Report

Merging #16 into develop will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           develop     #16   +/-   ##
=======================================
  Coverage     67.9%   67.9%           
=======================================
  Files           15      15           
  Lines        15826   15826           
  Branches      2283    2283           
=======================================
  Hits         10746   10746           
  Misses        4374    4374           
  Partials       706     706

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