[ELF] - Teach LLD to recognize PT_OPENBSD_BOOTDATA

Minor patch to fix PR31288

OpenBSD commit:
https://github.com/openbsd/src/commit/d39116912b9536bd77326260dc5c6e593fd4ee24

Differential revision: https://reviews.llvm.org/D27458

llvm-svn: 288832
diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index 366902c..f126ef0 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -1859,6 +1859,7 @@
                      .Case("PT_GNU_RELRO", PT_GNU_RELRO)
                      .Case("PT_OPENBSD_RANDOMIZE", PT_OPENBSD_RANDOMIZE)
                      .Case("PT_OPENBSD_WXNEEDED", PT_OPENBSD_WXNEEDED)
+                     .Case("PT_OPENBSD_BOOTDATA", PT_OPENBSD_BOOTDATA)
                      .Default(-1);
 
   if (Ret == (unsigned)-1) {