Merge #1661: configure: Show exhaustive tests in summary

20b05c9 configure: Show exhaustive tests in summary (Tim Ruffing)

Pull request description:

ACKs for top commit:
  hebasto:
    ACK 20b05c9, it aligns now with the CMake script: https://github.com/bitcoin-core/secp256k1/blob/e56716a3bcaf108bb7365ee8f2b06f9ec68504c8/CMakeLists.txt#L348-L350
  sipa:
    utACK 20b05c9
  jonasnick:
    ACK 20b05c9

Tree-SHA512: 30744ea5e5b7441ad252868c83cebfec2b02b75786b9ea55d4b0b0a696f1c7df39c48c243b29b13839a9f3a7757c192da8be0dd95412678a7583b123db6e99ac

Author: jonasnick

configure.ac

@@ -476,6 +476,7 @@ echo "Build Options:"
 echo "  with external callbacks = $enable_external_default_callbacks"
 echo "  with benchmarks         = $enable_benchmark"
 echo "  with tests              = $enable_tests"
+echo "  with exhaustive tests   = $enable_exhaustive_tests"
 echo "  with ctime tests        = $enable_ctime_tests"
 echo "  with coverage           = $enable_coverage"
 echo "  with examples           = $enable_examples"