[ELF] Set MAXPAGESIZE to 2MiB on x86-64 to match bfd and gold.

The FreeBSD kernel relies on this behavior to not overwrite the boot loader.

llvm-svn: 278889
diff --git a/lld/ELF/Target.cpp b/lld/ELF/Target.cpp
index ab71de3..8846137 100644
--- a/lld/ELF/Target.cpp
+++ b/lld/ELF/Target.cpp
@@ -545,6 +545,7 @@
 }
 
 template <class ELFT> X86_64TargetInfo<ELFT>::X86_64TargetInfo() {
+  MaxPageSize = 0x200000; // 2MiB
   CopyRel = R_X86_64_COPY;
   GotRel = R_X86_64_GLOB_DAT;
   PltRel = R_X86_64_JUMP_SLOT;