Merge bitcoin/bitcoin#22444: fuzz: Limit max ops in prevector fuzz target

faafda2 fuzz: Speed up prevector fuzz target (MarcoFalke)

Pull request description:

  Without a size limit on the input data, the runtime is unbounded. Fix this by picking an upper bound on the maximum number of fuzz operations.

  Should fix https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=35981

ACKs for top commit:
  practicalswift:
    cr ACK faafda2

Tree-SHA512: 1bf166c4a99a8ce88bdc030cd6a32ce1da5251b73873772e0e9c001ec2bacafebb183f7c8c88806d0ab633aada2cff8b78791f5c9c0c6f2cc8ef5f0875c4b2ef

Author: MarcoFalke

src/test/fuzz/prevector.cpp

@@ -206,10 +206,14 @@ class prevector_tester
 
 FUZZ_TARGET(prevector)
 {
+    // Pick an arbitrary upper bound to limit the runtime and avoid timeouts on
+    // inputs.
+    int limit_max_ops{3000};
+
     FuzzedDataProvider prov(buffer.data(), buffer.size());
     prevector_tester<8, int> test;
 
-    while (prov.remaining_bytes()) {
+    while (--limit_max_ops >= 0 && prov.remaining_bytes()) {
         switch (prov.ConsumeIntegralInRange<int>(0, 13 + 3 * (test.size() > 0))) {
         case 0:
             test.insert(prov.ConsumeIntegralInRange<size_t>(0, test.size()), prov.ConsumeIntegral<int>());