message: Automagically find nmake and vcvars64.bat
diff: @@ -9,26 +9,27 @@ execute_process(COMMAND git fetch
  if(WIN32)
  find_package(Perl REQUIRED)
  - set(NMAKE_64_EXECUTABLE NOT_FOUND CACHE FILEPATH "Path to x64 nmake.exe")
  - set(VCVARS64_BATCH_FILE NOT_FOUND CACHE FILEPATH
  - "Path to vcvar64.bat; usually something like C:/Program Files (x86)/Microsoft Visual Studio/2017/Community/VC/Auxiliary/Build/vcvars64.bat"
  + get_filename_component(
  + MY_COMPILER_DIR
  + ${CMAKE_CXX_COMPILER} DIRECTORY
  )
  -
  - if (NOT ${NMAKE_64_EXECUTABLE})
  - message(FATAL_ERROR "Path to nmake must be provided manually")
  - endif()
  - if (NOT ${VCVARS64_BATCH_FILE})
  + find_file(
  + VCVARS64_BAT vcvars64.bat
  + "${MY_COMPILER_DIR}/../../../../../../Auxiliary/Build"
  + )
  + if (NOT VCVARS64_BAT)
  + message(FATAL_ERROR "Tried ${VCVARS64_BAT}")
  message(FATAL_ERROR "Path to vcvars64.bat must be provided manually")
  endif()
  add_custom_command(
  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/build/lib/libeay32.lib" "${CMAKE_CURRENT_BINARY_DIR}/build/lib/ssleay32.lib"
  - COMMAND "${VCVARS64_BATCH_FILE}"
  + COMMAND "${VCVARS64_BAT}"
  COMMAND "${PERL_EXECUTABLE}" "${CMAKE_CURRENT_SOURCE_DIR}/openssl/Configure" VC-WIN64A no-asm --prefix=${CMAKE_CURRENT_BINARY_DIR}/build
  COMMAND "${CMAKE_CURRENT_SOURCE_DIR}/openssl/ms/do_win64a.bat"
  - COMMAND "${NMAKE_64_EXECUTABLE}" -f "${CMAKE_CURRENT_SOURCE_DIR}/openssl/ms/nt.mak"
  - COMMAND "${NMAKE_64_EXECUTABLE}" -f "${CMAKE_CURRENT_SOURCE_DIR}/openssl/ms/nt.mak" install
  + COMMAND "${CMAKE_MAKE_PROGRAM}" -f "${CMAKE_CURRENT_SOURCE_DIR}/openssl/ms/nt.mak"
  + COMMAND "${CMAKE_MAKE_PROGRAM}" -f "${CMAKE_CURRENT_SOURCE_DIR}/openssl/ms/nt.mak" install
  WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/openssl"
  COMMENT "Building OpenSSL..."
  VERBATIM
  