[CT-NG] toolchains built with GitHub actions

[abrodkin]

• Bare-metal toolchains
  • arc-multilib-elf32 - Little-endian ARCompact/ARCv2
  • arceb-multilib-elf32 - Big-endian ARCompact/ARCv2
  • arc64-unknown-elf - ARCv3 (both 32- & 64-bit)
• Linux toolchains
  • arc-arc700-linux-uclibc - ARC700 with uClibc
  • arc-archs-linux-uclibc - ARC HS38/48 with uClibc
  • arc-archs-linux-gnu - ARC HS38/48 with glibc
  • arc32-snps-linux-uclibc - ARC HS58 with uClibc
  • arc32-snps-linux-gnu - ARC HS58 with glibc
  • arc64-snps-linux-gnu - ARC HS68 with glibc

Canadian cross toolchains:

• Native (to be run on ARC targets)
  • arc-archs-native-gnu - ARC HS38/48 with glibc
  • arc32-snps-native-gnu - ARC HS58 with glibc
  • arc64-snps-native-gnu - ARC HS68 with glibc
• Foreign (to be run on non-Linux development hosts)
  • Windows 10 on x86_64 hosts
    • arc-elf32-win - bare-metal "multilib" toolchain for little-endian ARCompact/ARCv2 processor
    • arceb-elf32-win - bare-metal "multilib" toolchain for big-endian ARCompact/ARCv2 processors
    • arc64-elf-win - bare-metal "multilib" toolchain for little-endian ARCv3 processors
  • macOS on x86_64 hosts
    • arc-elf32-macos - bare-metal "multilib" toolchain for little-endian ARCompact/ARCv2 processors
    • arceb-elf32-macos - bare-metal "multilib" toolchain for big-endian ARCompact/ARCv2 processors
    • arc64-elf-macos - bare-metal "multilib" toolchain for little-endian ARCv3 processors