cmake: use imported targets for OpenSSL and zlib

Imported targets are highly preferred over the individual variables
for includes and libs because they will be used in a coherent way
and any spelling mistakes or unavailability won't go unnoticed.

Also it will prevent bugs like conan-io/conan-center-index#16900
or using mismatching header/libs combinations.

Signed-off-by: Gregor Jasny <gjasny@googlemail.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

tests/CMakeLists.txt

@@ -6,9 +6,7 @@ endif (BSD OR SOLARIS OR OSX)
 
 set(TORTURE_LIBRARY torture)
 
-include_directories(${OPENSSL_INCLUDE_DIR}
-                    ${CMOCKA_INCLUDE_DIR}
-                    ${ZLIB_INCLUDE_DIR}
+include_directories(${CMOCKA_INCLUDE_DIR}
                     ${libssh_BINARY_DIR}/include
                     ${libssh_BINARY_DIR}
                     ${libssh_SOURCE_DIR}/src

tests/external_override/CMakeLists.txt

@@ -44,7 +44,7 @@ else ()
         ${libssh_SOURCE_DIR}/src/md_crypto.c
     )
     set(override_libs
-        ${OPENSSL_CRYPTO_LIBRARIES}
+        OpenSSL::Crypto
     )
 endif (WITH_GCRYPT)
 

tests/pkd/CMakeLists.txt

@@ -5,7 +5,6 @@ if (WITH_SERVER AND UNIX AND NOT WIN32)
     include_directories(${libssh_SOURCE_DIR}/include
                         ${libssh_BINARY_DIR}/include
                         ${CMOCKA_INCLUDE_DIR}
-                        ${ZLIB_INCLUDE_DIR}
                         ${CMAKE_BINARY_DIR}
                         ${libssh_SOURCE_DIR}/src
                         ${CMAKE_CURRENT_SOURCE_DIR})

tests/unittests/CMakeLists.txt

@@ -1,7 +1,5 @@
 project(unittests C)
 
-include_directories(${OPENSSL_INCLUDE_DIR})
-
 set(LIBSSH_UNIT_TESTS
     torture_bignum
     torture_buffer