sync ports with The Matrix

devel/llvm/13/patches/patch-lld_ELF_SyntheticSections_cpp

@@ -0,0 +1,15 @@
+- Don't create IBT .plt if there are no PLT entries.  Cherry picked from
+  upstream.
+
+Index: lld/ELF/SyntheticSections.cpp
+--- lld/ELF/SyntheticSections.cpp.orig
++++ lld/ELF/SyntheticSections.cpp
+@@ -2729,6 +2729,8 @@ size_t IBTPltSection::getSize() const {
+   return 16 + in.plt->getNumEntries() * target->pltEntrySize;
+ }
+ 
++bool IBTPltSection::isNeeded() const { return in.plt->getNumEntries() > 0; }
++
+ // The string hash function for .gdb_index.
+ static uint32_t computeGdbHash(StringRef s) {
+   uint32_t h = 0;