Bound ssl_ctx_api more aggressively.

OpenSSL's d2i_X509 parser is amazingly slow. Only do about 10,000 of
them, not 1,000,000.

BUG=chromium:729419

Change-Id: I7034c3dde7d5c5681986af2ab5e516e54553d3c6
Reviewed-on: https://boringssl-review.googlesource.com/16905
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

fuzz/ssl_ctx_api.cc

diff --git a/fuzz/ssl_ctx_api.cc b/fuzz/ssl_ctx_api.cc
index 92cffb5..316980c 100644
--- a/fuzz/ssl_ctx_api.cc
+++ b/fuzz/ssl_ctx_api.cc
@@ -236,7 +236,7 @@
 }
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {
-  constexpr size_t kMaxExpensiveAPIs = 1000;
+  constexpr size_t kMaxExpensiveAPIs = 100;
   unsigned expensive_api_count = 0;
 
   const std::function<void(SSL_CTX *, CBS *)> kAPIs[] = {