asm_sym

The tracking issue for this feature is: #93333

This feature adds a sym <path> operand type to asm! and global_asm!.

• <path> must refer to a fn or static.
• A mangled symbol name referring to the item is substituted into the asm template string.
• The substituted string does not include any modifiers (e.g. GOT, PLT, relocations, etc).
• <path> is allowed to point to a #[thread_local] static, in which case the asm code can combine the symbol with relocations (e.g. @plt, @TPOFF) to read from thread-local data.