threadpool: allow leaf functions to run concurrently

Decrease the number of worker threads by one to account
for the fact the calling thread acts as a worker thread now

src/ringct/rctSigs.cpp

@@ -862,9 +862,9 @@ namespace rct {
                   results[i] = verBulletproof(rv.p.bulletproofs[i]);
                 else
                   results[i] = verRange(rv.outPk[i].mask, rv.p.rangeSigs[i]);
-              });
+              }, true);
             }
-            waiter.wait();
+            waiter.wait(&tpool);
 
             for (size_t i = 0; i < rv.outPk.size(); ++i) {
               if (!results[i]) {
@@ -970,9 +970,9 @@ namespace rct {
                 results[i] = verBulletproof(rv.p.bulletproofs[i]);
               else
                 results[i] = verRange(rv.outPk[i].mask, rv.p.rangeSigs[i]);
-            });
+            }, true);
           }
-          waiter.wait();
+          waiter.wait(&tpool);
 
           for (size_t i = 0; i < results.size(); ++i) {
             if (!results[i]) {
@@ -989,9 +989,9 @@ namespace rct {
           for (size_t i = 0 ; i < rv.mixRing.size() ; i++) {
             tpool.submit(&waiter, [&, i] {
                 results[i] = verRctMGSimple(message, rv.p.MGs[i], rv.mixRing[i], pseudoOuts[i]);
-            });
+            }, true);
           }
-          waiter.wait();
+          waiter.wait(&tpool);
 
           for (size_t i = 0; i < results.size(); ++i) {
             if (!results[i]) {