[tlbuild] texk/web2c/omegafonts/check.test: Inconsistent behaviour

[Johannes Hielscher]

Hi,

never ending mysteries in the test suite runs on powerpc-linux. Now
that there is a working fix for the utils/m-tx test, another test got
stubborn: texk/web2c/omegafonts/check.test reports failure on
executing ofm2opl with an ugly
  malloc(): memory corruption
error (attached: excerpt from texk/web2c/omegafonts/test-suite.log).
Needless to say that both the source code and the commands in test unit
haven't changed for over two years, and the script runs fine on any
other platform, as well as when I execute it from an interactive shell
(log also attached).
No difference between gcc-5.5.0/gcc-7.3.0, -O0/-O2. I am building on
Debian, where /bin/bash is a symlink to dash.

So, all tests do succeed (for now, in some constellation), so that one
can nontheless be quite confident in the binaries themselves. I am just
astonished that the tests' success may depend on the way of calling
them.