First real build setup for a 2019.02 release

[cgsfv]

Using the latest branches with the features agreed upon:

• gcc based on 8.2.0 code base with clic and lto patches
• binutils based on 2.32 code base with clic patches
• gdb based on FSF 8.3.0 branch (8.2.90) with the fixes from Andrew
• newlib is the same as for 2018.12 release
• openocd is the latest

Other changes from the previous way of building toolchain packages:

• The Makefile contains the newlib toolchain specific stuff from riscv-gnu-toolchain Makefile.in to make things simpler.
• The riscv-gcc/gcc/config/riscv/t-elf-multilib file which contains the multilibs configuration for the gcc newlib toolchain is generated from the Makefile by invoking the multilib-generator, which means that the multilibs configuration is not inherited from the gcc submodule itself.
• Debug info is not compiled into the outputs, by setting CFLAGS to "-O2" instead of the default "-g -O2".
• All outputs from configure, make and other scripts are piped to log files instead of polluting the console output.

[palmer-dabbelt]

Thanks!