cranelift: Add COFF TLS Support (#4546)

* cranelift: Implement COFF TLS Relocations

* cranelift: Emit SecRel relocations

* cranelift: Handle _tls_index symbol in backend

cranelift/codegen/src/binemit/mod.rs

@@ -35,6 +35,10 @@ pub enum Reloc {
     X86CallPLTRel4,
     /// x86 GOT PC-relative 4-byte
     X86GOTPCRel4,
+    /// The 32-bit offset of the target from the beginning of its section.
+    /// Equivalent to `IMAGE_REL_AMD64_SECREL`.
+    /// See: [PE Format](https://docs.microsoft.com/en-us/windows/win32/debug/pe-format)
+    X86SecRel,
     /// Arm32 call target
     Arm32Call,
     /// Arm64 call target. Encoded as bottom 26 bits of instruction. This
@@ -81,6 +85,7 @@ impl fmt::Display for Reloc {
             Self::X86CallPCRel4 => write!(f, "CallPCRel4"),
             Self::X86CallPLTRel4 => write!(f, "CallPLTRel4"),
             Self::X86GOTPCRel4 => write!(f, "GOTPCRel4"),
+            Self::X86SecRel => write!(f, "SecRel"),
             Self::Arm32Call | Self::Arm64Call => write!(f, "Call"),
 
             Self::ElfX86_64TlsGd => write!(f, "ElfX86_64TlsGd"),