esp-15.0.0-20220922

This is a release candidate.

Features:

• Upgrade LLVM version to 15.0.0
• Single toolchain for any Espressif chip (either Xtensa or RISCV architectures)
• Distribution for Linux ARM and ARM64 platforms. Closes #61.
• Distribution for MacOS ARM64 platform. Closes #61.
• Minimal distributions including libraries and headers only to be used by 3rd party tools (e.g. Espressif Rust port)
• Support Espressif vendor in target triple: xtensa-esp-elf and riscv32-esp-elf

Bug Fixes:

• [Xtensa] Fixes broken inline assembly memory operands. Closes #58.
• [Xtensa] Expand addi instruction with large immediate, to addmi + addi.
• [Xtensa] Implement support of .literal and .region directives in assembler parser.
• [Xtensa] Add bbci.l macro for bbci instruction and bbsi.l for bbsi.
• [Xtensa] Fix ill.n instruction encoding
• [Xtensa] Implement support of the --sysroot clang option. Closes #56.

Known issues:

• [Xtensa] Arguments wider than 32 bits are passed to functions incorrectly