tests fail on powerpc because ld prints extra unexpected warnings

[infinity0]

see e.g. https://buildd.debian.org/status/fetch.php?pkg=ocamlbuild&arch=powerpc&ver=0.11.0-1&stamp=1501347054&raw=0 :

�[m�[0;31m�[1m[FAILED]�[0m �[1mModularPlugin2      �[0;33mFailure with not matching message:
/usr/bin/ld: bss-plt forced due to /tmp/camlstartupb94de0.o
!=

.
�[m�[0;31m�[1m[FAILED]�[0m �[1mModularPlugin3      �[0;33mFailure with not matching message:
Warning: tag "toto" does not expect a parameter, but is used with parameter "-g"
/usr/bin/ld: bss-plt forced due to /tmp/camlstartupc32af9.o
!=
Warning: tag "toto" does not expect a parameter, but is used with parameter "-g"
.
�[m�[0;32m�[1m[PASSED]�[0m �[1mPluginCompilation1  �[0;36mcheck that the plugin is not compiled when -no-plugin is passed.
�[m�[0;32m�[1m[PASSED]�[0m �[1mPluginCompilation2  �[0;36mcheck that the plugin is compiled when -just-plugin is passed.
�[m�[0;31m�[1m[FAILED]�[0m �[1mPluginCompilation3  �[0;33mFailure with not matching message:
/usr/bin/ld: bss-plt forced due to /tmp/camlstartupf1498f.o
!=

.

In fact the underlying issue is due to ocaml itself, but these extra warnings don't seem to affect ocaml's own testsuite which passes despite the warnings.

Googling the error message suggests this may be a potential security weakness as the alternative to bss-plt is called "secure-plt" [1] [2]. I don't know if you care about it though since powerpc is not really a common platform.

I can file this over on the ocaml mantis BT tracker too if that would be more appropriate. In the meantime I will see if I can have ocamlbuild on Debian powerpc ignore these extra warnings in the same way that ocaml's own testsuite does.