[oe] [meta-java] gcc6 support breaks build for gcc < 6

[Winfried]

> If you are not using default compiler then you have to take some action
> 
> add
> 
> CFLAGS_remove = " -fno-tree-dse"
> CXXFLAGS_remove = " -fno-tree-dse"
> 
> via a .bbappend in your layer.

Yes, to let meta-java compile with gcc 4.8 I added the following lines 
to a .bbappend file:

CFLAGS_remove = "-fno-lifetime-dse"
CXXFLAGS_remove = "-fno-lifetime-dse"

If that is the final solution, please add this to the README of the 
meta-java layer.

Thanks,
Winfried