Revert "libcpprestsdk: fix building as a static library (microsoft#1344)"

This reverts commit cb7ca74.

Issues concerning OpenSSL linking dependency (microsoft#1384, microsoft#1388)
and cross compiling (microsoft#1378) have been reported.

- Fixes microsoft#1384, microsoft#1388

Author: c72578

Release/cmake/cpprest_find_openssl.cmake

@@ -43,15 +43,7 @@ function(cpprest_find_openssl)
       message(STATUS "OPENSSL_ROOT_DIR = ${OPENSSL_ROOT_DIR}")
       set(_OPENSSL_VERSION "")
     endif()
-    if(UNIX)
-      find_package(PkgConfig)
-      pkg_search_module(OPENSSL openssl)
-    endif()
-    if(OPENSSL_FOUND)
-      target_link_libraries(cpprest PRIVATE ${OPENSSL_LDFLAGS})
-    else()
-      find_package(OpenSSL 1.0.0 REQUIRED)
-    endif()
+    find_package(OpenSSL 1.0.0 REQUIRED)
 
     INCLUDE(CheckCXXSourceCompiles)
     set(CMAKE_REQUIRED_INCLUDES "${OPENSSL_INCLUDE_DIR}")
@@ -77,4 +69,4 @@ function(cpprest_find_openssl)
     # libressl doesn't ship with the cleanup method being used in ws_client_wspp
     target_compile_definitions(cpprestsdk_openssl_internal INTERFACE -DCPPREST_NO_SSL_LEAK_SUPPRESS)
   endif()
-endfunction()
+endfunction()