Support cross compiling kernels with GCC6

• aportgen: modify code to allow generating gcc6-armhf and other gcc6 cross compiler packages
• package: when 'gcc6' is in the depends of a package, and the cross compiling mode is "native" (as we do it with kernels), install the gcc6 cross compiler instead of the usual one (gcc8)

(reviews would be nice, but this is so urgent that I'll continue ASAP anyway even if nobody reviews it. I know that this will probably not pass CI right now.)

Related: pmaports#103 (closed)

mentioned in commit pmaports@27f31bcc

By Oliver Smith on 2018-09-30T02:40:45

No test case breakage? Awesome. Then I'll merge this, update the gcc6-armhf and gcc6-aarch64 abuilds, then let them compile tonight.

By Oliver Smith on 2018-09-30T02:49:53

unmarked as a Work In Progress

By Oliver Smith on 2018-09-30T02:50:18

changed the description

By Oliver Smith on 2018-09-30T02:50:18

merged

By Oliver Smith on 2018-09-30T02:52:12

mentioned in commit pmaports@370914c2

By Oliver Smith on 2018-10-05T15:51:16

mentioned in commit pmaports@7bff136e

By Oliver Smith on 2018-11-27T06:58:15