CrayPE fix for kvtree (#23513)

Allow for multiple definitions at link time (with cce's linker)

Co-authored-by: Tamara Dahlgren <35777542+tldahlgren@users.noreply.github.com>

var/spack/repos/builtin/packages/kvtree/package.py

@@ -30,6 +30,12 @@ class Kvtree(CMakePackage):
             multi=False,
             description='File locking style for KVTree.')
 
+    def flag_handler(self, name, flags):
+        if self.spec.satisfies('%cce'):
+            if name == 'ldflags':
+                flags.append('-Wl,-z,muldefs')
+            return (flags, None, None)
+
     def cmake_args(self):
         args = []
         if self.spec.satisfies('+mpi'):