CMake: Build everything with -Werror

When COMPILE_WARNING_AS_ERROR is set, compile everything with -Werror
and not just Libiio.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>

CMakeLists.txt

@@ -305,7 +305,7 @@ if (MSVC)
 	# Azure Pipelines: TF_BUILD=True
 	if(COMPILE_WARNING_AS_ERROR)
 		message(STATUS "Setting -Werror")
-		target_compile_options(iio PRIVATE /WX)
+		target_compile_options(iio PUBLIC /WX)
 	endif()
 elseif (CMAKE_C_COMPILER_ID MATCHES "GNU|Clang")
 	option(WITH_GCOV "Build with gcov profiling flags" OFF)
@@ -318,7 +318,7 @@ elseif (CMAKE_C_COMPILER_ID MATCHES "GNU|Clang")
 	endif()
 	if(COMPILE_WARNING_AS_ERROR)
 		message(STATUS "Setting -Werror")
-		target_compile_options(iio PRIVATE -Werror)
+		target_compile_options(iio PUBLIC -Werror)
 	endif()
 else()
 	message(STATUS "Unknown compiler ${CMAKE_C_COMPILER_ID}")