#535 [lxtask] fix multiple definitions of global variables (builds with -fno-common)

[Hanno Böck]

In lxtask there are a couple of global variables defined in headers that get included multiple times. gcc traditionally ignores such issues and allows multiple definitions, however it's not correct C code. One can get gcc to behave more strictly with the parameter -fno-common.

The attached patch fixes all multiple definitions. Two variables - custom_signal_0 and custom_signal_1 - don't seem to be used at all, so I removed them. Several variables in interface.h need to be made external, the main variable definition got moved to interface.c.

[Mamoru TASAKA]

gcc10 now defaults to -fno-common :
https://gcc.gnu.org/gcc-10/changes.html

So without this patch, lxtask fails to compile with gcc10. Please review and consider to apply this.

[Lonely Stranger]

Thank you very much for your fix. That's sad it left unnoticed for so long time.