DynamicLoader: Add RTLD_GLOBAL as a supported flag on linux

DynamicLoader.cxx

@@ -436,9 +436,14 @@ namespace KWSYS_NAMESPACE {
 DynamicLoader::LibraryHandle DynamicLoader::OpenLibrary(
   const std::string& libname, int flags)
 {
-  CHECK_OPEN_FLAGS(flags, 0, nullptr);
+  CHECK_OPEN_FLAGS(flags, RTLDGlobal, nullptr);
+
+  int llFlags = RTLD_LAZY;
+  if (flags & RTLDGlobal) {
+    llFlags |= RTLD_GLOBAL;
+  }
 
-  return dlopen(libname.c_str(), RTLD_LAZY);
+  return dlopen(libname.c_str(), llFlags);
 }
 
 int DynamicLoader::CloseLibrary(DynamicLoader::LibraryHandle lib)

DynamicLoader.hxx.in

@@ -73,7 +73,12 @@ public:
     // This is currently only supported on Windows.
     SearchBesideLibrary = 0x00000001,
 
-    AllOpenFlags = SearchBesideLibrary
+    // Make loaded symbols visible globally
+    //
+    // This is currently only supported on *nix systems.
+    RTLDGlobal = 0x00000002,
+
+    AllOpenFlags = SearchBesideLibrary | RTLDGlobal
   };
 
   /** Load a dynamic library into the current process.