Remove reloc_block

It isn't called and all reloc sinks either ignore it or panic when it is
called.

cranelift/filetests/src/test_binemit.rs

@@ -72,10 +72,6 @@ impl binemit::CodeSink for TextSink {
         self.offset += 8;
     }
 
-    fn reloc_block(&mut self, reloc: binemit::Reloc, block_offset: binemit::CodeOffset) {
-        write!(self.text, "{}({}) ", reloc, block_offset).unwrap();
-    }
-
     fn reloc_external(
         &mut self,
         _srcloc: ir::SourceLoc,

cranelift/filetests/src/test_compile.rs

@@ -109,7 +109,6 @@ impl binemit::CodeSink for SizeSink {
         self.offset += 8;
     }
 
-    fn reloc_block(&mut self, _reloc: binemit::Reloc, _block_offset: binemit::CodeOffset) {}
     fn reloc_external(
         &mut self,
         _srcloc: ir::SourceLoc,

cranelift/filetests/src/test_rodata.rs

@@ -106,7 +106,6 @@ impl binemit::CodeSink for RodataSink {
         }
     }
 
-    fn reloc_block(&mut self, _reloc: binemit::Reloc, _block_offset: binemit::CodeOffset) {}
     fn reloc_external(
         &mut self,
         _: ir::SourceLoc,

cranelift/filetests/src/test_stack_maps.rs

@@ -79,7 +79,6 @@ impl CodeSink for TestStackMapsSink {
         self.offset += 8;
     }
 
-    fn reloc_block(&mut self, _: Reloc, _: CodeOffset) {}
     fn reloc_external(&mut self, _: SourceLoc, _: Reloc, _: &ExternalName, _: Addend) {}
     fn reloc_constant(&mut self, _: Reloc, _: ConstantOffset) {}
     fn reloc_jt(&mut self, _: Reloc, _: JumpTable) {}