[ELF] Remove unused functions. NFC (llvm#195546)

Author: MaskRay

lld/ELF/InputSection.h

@@ -209,11 +209,6 @@ class InputSectionBase : public SectionBase {
     bytesDropped += num;
   }
 
-  void push_back(uint64_t num) {
-    assert(bytesDropped >= num);
-    bytesDropped -= num;
-  }
-
   mutable const uint8_t *content_;
   uint64_t size;
 

lld/ELF/Target.h

@@ -42,7 +42,6 @@ class TargetInfo {
   virtual void writeGotPlt(uint8_t *buf, const Symbol &s) const {}
   virtual void writeIgotPlt(uint8_t *buf, const Symbol &s) const {}
   virtual int64_t getImplicitAddend(const uint8_t *buf, RelType type) const;
-  virtual int getTlsGdRelaxSkip(RelType type) const { return 1; }
 
   // If lazy binding is supported, the first entry of the PLT has code
   // to call the dynamic linker to resolve PLT entries the first time