Request C++11 standard project-wise and make it a strong requirement.

It is unneeded to do it by target, using the globale property
CMAKE_CXX_STANDARD instead. Also with CMAKE_CXX_STANDARD_REQUIRED, I
make this a strong requirement. The documentation indeed states that the
CXX_STANDARD "is treated as optional and may “decay” to a previous
standard if the requested is not available".
This means that uchardet will likely not be buildable with a compiler
with no C++11 support. But I assume this is not a common situation, and
probably we should not care about outdated compilers. I remain open to
suggestions and disagreement on the topic obviously.

CMakeLists.txt

@@ -19,6 +19,8 @@ set (
 	UCHARDET_VERSION
 	${UCHARDET_VERSION_MAJOR}.${UCHARDET_VERSION_MINOR}.${UCHARDET_VERSION_REVISION}${version_suffix}
 )
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 ######## Windows
 

src/CMakeLists.txt

@@ -79,8 +79,6 @@ add_library(
 	${UCHARDET_LIBRARY}
 	${UCHARDET_SOURCES}
 )
-set_property(TARGET ${UCHARDET_LIBRARY}
-             PROPERTY CXX_STANDARD 11)
 
 if (UCHARDET_STATIC_LIBRARY)
 	add_library(
@@ -88,8 +86,6 @@ if (UCHARDET_STATIC_LIBRARY)
 		STATIC
 		${UCHARDET_SOURCES}
 	)
-    set_property(TARGET ${UCHARDET_STATIC_LIBRARY}
-                 PROPERTY CXX_STANDARD 11)
 endif (UCHARDET_STATIC_LIBRARY)
 
 set_target_properties(

src/tools/CMakeLists.txt

@@ -9,8 +9,6 @@ add_executable(
 	${UCHARDET_BINARY}
 	${UCHARDET_SOURCES}
 )
-set_property(TARGET ${UCHARDET_BINARY}
-             PROPERTY CXX_STANDARD 11)
 
 target_link_libraries(
 	${UCHARDET_BINARY}

test/CMakeLists.txt

@@ -7,8 +7,6 @@ add_executable(
 	uchardet-tests
 	${UCHARDET_TEST_SOURCES}
 )
-set_property(TARGET uchardet-tests
-             PROPERTY CXX_STANDARD 11)
 
 target_link_libraries(
 	uchardet-tests