Allways export function ngCM_Input_Path, independently from XSPICE

Update comment

src/sharedspice.c

@@ -1102,13 +1102,15 @@ int  ngSpice_Command(char* comexec)
     return 1;
 }
 
-#ifdef XSPICE
-/* Set the input path for files loaded by code models.
+/* Set the input path for files loaded by code models
+   like d_state, file_source, d_source.
+   Useful when netlist is sent by ngSpice_Circ and therefore
+   Infile_Path cannot be retrieved automatically.
    If NULL is sent, return the current Infile_Path. */
 IMPEXP
 char *ngCM_Input_Path(const char* path)
 {
-    /* delete existing command memory */
+    /* override existing path */
     if (path) {
         txfree(Infile_Path);
         Infile_Path = copy(path);
@@ -1116,7 +1118,6 @@ char *ngCM_Input_Path(const char* path)
     fprintf(stdout, "Note: Codel model file loading path is %s\n", Infile_Path);
     return Infile_Path;
 }
-#endif
 
 /* Return information about a vector to the caller */
 IMPEXP
@@ -1357,6 +1358,7 @@ int ngSpice_UnlockRealloc(void)
     return 1;
 }
 
+
 /* add the preliminary breakpoints to the list.
    called from dctran.c */
 int