Added to cmake environment CMAKE_DL_LIBS (The name of the library
that has dlopen and dlclose in it, usually -ldl) to openssl build
to add DL library, to fix the following fails:

Linking CXX executable crypto.test
/usr/local/lib64/libcrypto.a(dso_dlfcn.o): In function `dlfcn_globallookup':
dso_dlfcn.c:(.text+0x11): undefined reference to `dlopen'
dso_dlfcn.c:(.text+0x24): undefined reference to `dlsym'
dso_dlfcn.c:(.text+0x2f): undefined reference to `dlclose'
/usr/local/lib64/libcrypto.a(dso_dlfcn.o): In function `dlfcn_bind_func':
dso_dlfcn.c:(.text+0x334): undefined reference to `dlsym'
dso_dlfcn.c:(.text+0x3f2): undefined reference to `dlerror'
/usr/local/lib64/libcrypto.a(dso_dlfcn.o): In function `dlfcn_load':
dso_dlfcn.c:(.text+0x459): undefined reference to `dlopen'
dso_dlfcn.c:(.text+0x4c9): undefined reference to `dlclose'
dso_dlfcn.c:(.text+0x502): undefined reference to `dlerror'
/usr/local/lib64/libcrypto.a(dso_dlfcn.o): In function `dlfcn_pathbyaddr':
dso_dlfcn.c:(.text+0x5a1): undefined reference to `dladdr'
dso_dlfcn.c:(.text+0x601): undefined reference to `dlerror'
/usr/local/lib64/libcrypto.a(dso_dlfcn.o): In function `dlfcn_unload':
dso_dlfcn.c:(.text+0x662): undefined reference to `dlclose'
collect2: error: ld returned 1 exit status
make[2]: *** [test/unit/crypto.test] Error 1
make[1]: *** [test/unit/CMakeFiles/crypto.test.dir/all] Error 2

Closes #4245