Switch to gcc 10.5

[thatguywiththekids]

This PR introduces a new patch for gcc 10.5.0, changes regcall stuff so it works with the new compiler (less reliant on C compiler behavior) and makes some other adjustments for stack alignment and inline assembler compatibility. -mno-red-zone is enabled by default for x86/x86-64 to make interrupt handling and regcall more reliable. The default gcc version is updated to 10.5.0.