make pre-processor defines for using libc's qsort() consistent

src/dump.h

@@ -33,7 +33,7 @@ class Dump : protected Pointers {
   int comm_forward;          // size of forward communication (0 if none)
   int comm_reverse;          // size of reverse communication (0 if none)
 
-#if defined(LMP_USE_LIBC_QSORT)
+#if defined(LMP_QSORT)
   // static variable across all Dump objects
   static Dump *dumpptr;         // holds a ptr to Dump currently being used
 #endif
@@ -135,7 +135,7 @@ class Dump : protected Pointers {
   void pbc_allocate();
 
   void sort();
-#if defined(LMP_USE_LIBC_QSORT)
+#if defined(LMP_QSORT)
   static int idcompare(const void *, const void *);
   static int bufcompare(const void *, const void *);
   static int bufcompare_reverse(const void *, const void *);

src/irregular.h

@@ -21,7 +21,7 @@ namespace LAMMPS_NS {
 class Irregular : protected Pointers {
  public:
 
-#if defined(LMP_USE_LIBC_QSORT)
+#if defined(LMP_QSORT)
   // static variable across all Irregular objects, for qsort callback
 
   static int *proc_recv_copy;