[upstreaming] Revert adding empty implementation of deregisterEHFrames

We already disabled the registration, so this is no-op.

Author: Teemperor

lldb/include/lldb/Expression/IRExecutionUnit.h

@@ -310,10 +310,6 @@ class IRExecutionUnit : public std::enable_shared_from_this<IRExecutionUnit>,
     void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr,
                           size_t Size) override {}
 
-    virtual void deregisterEHFrames() override {
-      return;
-    }
-
     uint64_t getSymbolAddress(const std::string &Name) override;
 
     // Find the address of the symbol Name.  If Name is a missing weak symbol