cmake: Build ssh_server_fuzzer if enabled

Fixes T67

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>

cmake/Modules/FindClangFuzzer.cmake

@@ -0,0 +1,32 @@
+# - Try to find Fuzzer
+# Once done this will define
+#
+#  CLANG_FUZZER_FOUND - system has Fuzzer
+#  CLANG_FUZZER_LIBRARY - Link these to use Fuzzer
+#
+#=============================================================================
+#  Copyright (c) 2018 Andreas Schneider <asn@cryptomilk.org>
+#
+#  Distributed under the OSI-approved BSD License (the "License");
+#  see accompanying file Copyright.txt for details.
+#
+#  This software is distributed WITHOUT ANY WARRANTY; without even the
+#  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+#  See the License for more information.
+#=============================================================================
+#
+
+find_package(Clang REQUIRED CONFIG)
+
+find_library(CLANG_FUZZER_LIBRARY
+    NAMES
+        Fuzzer
+    HINTS
+        ${LLVM_LIBRARY_DIR}/clang/${LLVM_PACKAGE_VERSION}/lib
+)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Fuzzer DEFAULT_MSG CLANG_FUZZER_LIBRARY)
+
+# show the CLANG_FUZZER_LIBRARY variables only in the advanced view
+mark_as_advanced(CLANG_FUZZER_LIBRARY)