[gdbsupport] Ignore pathc in codespell check in gdb_tilde_expand.cc

Ignore the following codespell detections:
...
$ codespell --config gdbsupport/setup.cfg gdbsupport
gdbsupport/gdb_tilde_expand.cc:54: pathc ==> patch
gdbsupport/gdb_tilde_expand.cc:99: pathc ==> patch
...
by adding codespell:ignore comments.
diff --git a/gdbsupport/gdb_tilde_expand.cc b/gdbsupport/gdb_tilde_expand.cc
index 4a0a573..f009979 100644
--- a/gdbsupport/gdb_tilde_expand.cc
+++ b/gdbsupport/gdb_tilde_expand.cc
@@ -51,7 +51,7 @@
   }
 
   /* Return the GL_PATHC component of M_GLOB.  */
-  int pathc () const
+  int pathc () const /* codespell:ignore */
   {
     return m_glob.gl_pathc;
   }
@@ -96,6 +96,6 @@
 
   const gdb_glob glob (to_expand.c_str (), GLOB_TILDE_CHECK, nullptr);
 
-  gdb_assert (glob.pathc () == 1);
+  gdb_assert (glob.pathc () == 1); /* codespell:ignore */
   return std::string (glob.pathv ()[0]) + remainder;
 }