Rename getSizeOfHeaders -> getHeaderSize.

We have getSectionSize for SIZEOF command. So, I think
getHeaderSize is a better name for SIZEOF_HEADERS.

llvm-svn: 278470
diff --git a/lld/ELF/LinkerScript.h b/lld/ELF/LinkerScript.h
index 8029c74..ecf9f5c 100644
--- a/lld/ELF/LinkerScript.h
+++ b/lld/ELF/LinkerScript.h
@@ -151,7 +151,7 @@
   int compareSections(StringRef A, StringRef B);
   bool hasPhdrsCommands();
   uintX_t getOutputSectionSize(StringRef Name);
-  uintX_t getSizeOfHeaders();
+  uintX_t getHeaderSize();
 
   std::vector<OutputSectionBase<ELFT> *> *OutputSections;