[MELT] Several build fix

[Romain Geissler <romain dot geissler at gmail dot com>]

Hello,

Here is a little patch that fix build on my red hat system. It should work for both the plugin and the branch version (although i could not generate the new plugin because upgrade-warmelt require unifdef that i don't have on my system, so the plugin version has not been tested directly from the branch source tarball).

Please check if it still work for you, i may have broken things !

(this includes

@Basile Do not read this until you're back from your vacation.
I've corrected the bug dealing with unfound c sources files to build existing module so files
I have also added a -Wno-error switch in the check-melt-runtime so that it doesn't break the whole build (as it uses -Werror by default on my system). But this should be only a temporary workaround, as you noticed some days warmelt-ana-simple detects bugs in the runtime, and this should be corrected. There is mostly meltgc_* functions that do no declare a MELT_ENTERFRAME. I don't really understand why and when there is a need for such, so i let you correct that. When it's done, do not forget to remove the -Wno-error switch.

The plugin version should now be a little bit more configurable thanks to  variable ?= value assignements. In particular, we can use a custom gcc and not the one in PATH, and add some library includes thanks to LIBS_INCLUDEFLAGS (useful when ppl is not in the default include directory for example).

I will now try to patch the trunk to build twice and install gengtype when plugins are available.

Attachment: build.diff
Description: Binary data

Attachment: build.Changelog
Description: Binary data