lld-link: Implement /INTEGRITYCHECK flag

/INTEGRITYCHECK has the effect of setting
IMAGE_DLLCHARACTERISTICS_FORCE_INTEGRITY. Fixes PR31066.
https://reviews.llvm.org/D47472

llvm-svn: 333652
diff --git a/lld/COFF/Options.td b/lld/COFF/Options.td
index a6ef2ff..9051b0b 100644
--- a/lld/COFF/Options.td
+++ b/lld/COFF/Options.td
@@ -117,7 +117,10 @@
                        "Disable 64-bit ASLR">;
 defm incremental : B<"incremental",
                      "Keep original import library if contents are unchanged",
-                     "Replace import library file even if contents are unchanged">;
+                     "Overwrite import library even if contents are unchanged">;
+defm integritycheck : B<"integritycheck",
+                        "Set FORCE_INTEGRITY bit in PE header",
+                        "No effect (default)">;
 defm largeaddressaware : B<"largeaddressaware",
                            "Enable large addresses (default on 64-bit)",
                            "Disable large addresses (default on 32-bit)">;