[OpenMP][libomptarget] Minor fix in x86_64 plugin

Call to remove() was passing invalid address for the file name.

Differential Revision: https://reviews.llvm.org/D109846

openmp/libomptarget/plugins/generic-elf-64bit/src/rtl.cpp

@@ -41,7 +41,7 @@
 
 /// Array of Dynamic libraries loaded for this target.
 struct DynLibTy {
-  char *FileName;
+  std::string FileName;
   void *Handle;
 };
 
@@ -100,7 +100,7 @@ public:
     for (auto &lib : DynLibs) {
       if (lib.Handle) {
         dlclose(lib.Handle);
-        remove(lib.FileName);
+        remove(lib.FileName.c_str());
       }
     }
   }