CI/darwin test: find installed openssl (homebrew)

bin/ci

@@ -86,7 +86,7 @@ format() {
 prepare_build() {
   on_linux verify_linux_environment
 
-  on_osx brew install crystal
+  on_osx brew install crystal pkg-config
 
   # Make sure binaries from llvm are available in PATH
   on_osx brew install jq
@@ -112,6 +112,9 @@ with_build_env() {
   # Ensure non GMT timezone
   export TZ="America/New_York"
 
+  # ensure to find recent openssl version (may be removed on macOS 10.13 ?):
+  on_osx export PKG_CONFIG_PATH="/usr/local/opt/openssl/lib/pkgconfig"
+
   on_linux verify_linux_environment
 
   export DOCKER_TEST_PREFIX="crystallang/crystal:0.27.0"
@@ -138,7 +141,6 @@ with_build_env() {
   on_osx PATH="/usr/local/opt/llvm/bin:\$PATH" \
     CRYSTAL_CACHE_DIR="/tmp/crystal" \
     /bin/sh -c "'$command'"
-
 }
 
 usage() {

src/openssl/version.sh

@@ -4,8 +4,8 @@
 CFLAGS=`command -v pkg-config > /dev/null && pkg-config --cflags --silence-errors $1 || true`
 
 # extract version numbers from OpenSSL/LibreSSL C headers:
-LIBRESSL_VERSION_NUMBER=$(printf "#include <openssl/opensslv.h>\nLIBRESSL_VERSION_NUMBER" | ${CC:-cc} $CFLAGS -E - 2> /dev/null | tail -n 1)
-OPENSSL_VERSION_NUMBER=$(printf "#include <openssl/opensslv.h>\nOPENSSL_VERSION_NUMBER" | ${CC:-cc} $CFLAGS -E - 2> /dev/null | tail -n 1)
+LIBRESSL_VERSION_NUMBER=$(printf "#include <openssl/opensslv.h>\nLIBRESSL_VERSION_NUMBER" | ${CC:-cc} $CFLAGS -E - | tail -n 1)
+OPENSSL_VERSION_NUMBER=$(printf "#include <openssl/opensslv.h>\nOPENSSL_VERSION_NUMBER" | ${CC:-cc} $CFLAGS -E - | tail -n 1)
 
 if [ $LIBRESSL_VERSION_NUMBER = LIBRESSL_VERSION_NUMBER ]; then
     # detected OpenSSL: