libgpg-error: Support build for native on ppc host
In Ubuntu 16.04 LTS userspace is build for PowerPC 32-bit while kernel
selected by the installer depending on PowerPC machine type:
* 32-bit for PowerMac G4 (ppc7400) and below
* 64-bit for PowerMac G5 and above
Thus uname(2) returns ppc64 for 64-bit kernels and 32-bit userspace
making build impossible due to missing some of lib64 multilib
equivalents in Ubuntu repository.
Using setarch(8) override to make whole host look as PowerPC 32-bit
can actually help with build but requires mapping for ppc target to
their libgpg-error equivalent to fix native build.
Build tested on Ubuntu 16.04 LTS host on PowerMac G5 with command:
