[DO-971] ffmpeg recipe with requirements (!9)

Co-authored-by: aleksandr.vodyanov <aleksandr.vodyanov@avroid.tech>
Reviewed-on: https://git.avroid.tech/Conan/conan_build/pulls/9

recipes/openjpeg/all/test_package/CMakeLists.txt

@@ -0,0 +1,25 @@
+cmake_minimum_required(VERSION 3.1)
+project(test_package LANGUAGES C)
+
+find_package(OpenJPEG REQUIRED CONFIG)
+
+add_executable(${PROJECT_NAME} test_package.c)
+target_link_libraries(${PROJECT_NAME} PRIVATE openjp2)
+
+# Test whether variables from https://github.com/uclouvain/openjpeg/blob/master/cmake/OpenJPEGConfig.cmake.in are properly defined
+set(_custom_vars
+    OPENJPEG_FOUND
+    OPENJPEG_INCLUDE_DIRS
+    OPENJPEG_LIBRARIES
+    OPENJPEG_MAJOR_VERSION
+    OPENJPEG_MINOR_VERSION
+    OPENJPEG_BUILD_VERSION
+    OPENJPEG_BUILD_SHARED_LIBS
+)
+foreach(_custom_var ${_custom_vars})
+    if(DEFINED ${_custom_var})
+        message(STATUS "${_custom_var}: ${${_custom_var}}")
+    else()
+        message(FATAL_ERROR "${_custom_var} not defined")
+    endif()
+endforeach()