[ELF] Support -z max-page-size option

This options issupported by both BFD ld and gold and allows
overriding the max page size whose default values are defined by
the target.

https://llvm.org/bugs/show_bug.cgi?id=30541

Differential Revision: https://reviews.llvm.org/D24891

llvm-svn: 282596
diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index d350b5c..e9885d4 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -1472,7 +1472,7 @@
   if (S == "COMMONPAGESIZE")
     return Target->PageSize;
   if (S == "MAXPAGESIZE")
-    return Target->MaxPageSize;
+    return Config->MaxPageSize;
   error("unknown constant: " + S);
   return 0;
 }