Add conda compilers

[gaiar]

Recipes for conda-build 3.x compilers with configs

[jjhelmus]

Where you able to get the compilers to build on a Raspberry Pi? When I tried to build this on my RPi 3B+ via conda build -m conda_build_config.rpi3_armv7le.yaml -c gaiar . it failed with the following in the build.log:

[ALL  ]    /bin/bash ../libtool  --tag=CC   --mode=compile armv7l-build_unknown-linux-gnueabihf-gcc -DHAVE_CONFIG_H -I. -I/home/jhelmus/bc3_v7/conda-bld/compilers
_linux-armv7l_1533597228609/work/.build/armv7-rpi3-linux-gnueabihf/src/gmp/mpn -I..  -D__GMP_WITHIN_GMP -I/home/jhelmus/bc3_v7/conda-bld/compilers_linux-armv7l_15
33597228609/work/.build/armv7-rpi3-linux-gnueabihf/src/gmp -DOPERATION_`echo mod_1 | sed 's/_$//'`   -O2 -g -pipe -I/home/jhelmus/bc3_v7/conda-bld/compilers_linux
-armv7l_1533597228609/work/.build/armv7-rpi3-linux-gnueabihf/buildtools/include   -fexceptions -c -o mod_1.lo mod_1.c
[ALL  ]    tmp-divrem_1.s: Assembler messages:         
[ALL  ]    tmp-divrem_1.s:129: Error: selected processor does not support `mls r1,r4,r8,r11' in ARM mode
[ALL  ]    tmp-divrem_1.s:145: Error: selected processor does not support `mls r1,r4,r8,r11' in ARM mode                                                          
[ALL  ]    tmp-divrem_1.s:158: Error: selected processor does not support `mls r1,r4,r8,r11' in ARM mode
[ALL  ]    tmp-divrem_1.s:175: Error: selected processor does not support `mls r1,r4,r3,r8' in ARM mode
[ALL  ]    tmp-divrem_1.s:209: Error: selected processor does not support `mls r11,r4,r12,r3' in ARM mode

I was able to build these on a system running the Debian armhf port.

[gaiar]

Raspbian repo has outdated gcc build, supporting only ARMV6 instructions.
To built compilers using these configs on RPI3 you have to update gcc first.
For that, I was using such script - https://gist.github.com/gaiar/17463ccdbc7c06b9090f192a8baff2cb

Takes half a day on RPI3 and more than 3 days on RPI Zero O_o

Disclaimer: Seems that conda-forge is using custom fork of crosstool, which lacks configs for aarch64, so I'm checking how to build ARM64 compilers.