build: clean up NO_GETTEXT cmake support

Make NO_GETTEXT a build option aliased to ENV{NO_GETTEXT} to pass to
vcpkg_install.bat to skip building gettext.

Turn it off by default when vcpkg is in-use because it's a very long
compile.

Also do not build translations if NO_GETTEXT is set.

Signed-off-by: Rafael Kitover <rkitover@gmail.com>

contrib/buildsystems/CMakeLists.txt

@@ -72,6 +72,21 @@ if(NOT WIN32)
 	set(USE_VCPKG OFF CACHE BOOL FORCE)
 endif()
 
+set(gettext_default TRUE)
+
+# Turn off gettext by default when using vcpkg because it's a very
+# long compile.
+if(NOT USE_VCPKG)
+	set(gettext_default FALSE)
+endif()
+
+build_option(
+	NO_GETTEXT
+	BOOL "Set to TRUE/ON to disable internationalization support using gettext and building translations using msgfmt from gettext-tools."
+	${gettext_default}
+	ALIASES ENV{NO_GETTEXT}
+)
+
 if(NOT DEFINED CMAKE_EXPORT_COMPILE_COMMANDS)
 	set(CMAKE_EXPORT_COMPILE_COMMANDS TRUE)
 	message("settting CMAKE_EXPORT_COMPILE_COMMANDS: ${CMAKE_EXPORT_COMPILE_COMMANDS}")
@@ -195,8 +210,7 @@ find_package(CURL)
 find_package(EXPAT)
 find_package(Iconv)
 
-#Don't use libintl on Windows Visual Studio and Clang builds
-if(NOT (WIN32 AND (CMAKE_C_COMPILER_ID STREQUAL "MSVC" OR CMAKE_C_COMPILER_ID STREQUAL "Clang")))
+if(NOT NO_GETTEXT)
 	find_package(Intl)
 endif()
 
@@ -229,18 +243,10 @@ if(WIN32 AND NOT MSVC)#not required for visual studio builds
 	endif()
 endif()
 
-if(NO_GETTEXT)
-	message(STATUS "msgfmt not used under NO_GETTEXT")
-else()
+if(NOT NO_GETTEXT)
 	find_program(MSGFMT_EXE msgfmt)
 	if(NOT MSGFMT_EXE)
-		if(USE_VCPKG)
-			set(MSGFMT_EXE ${CMAKE_SOURCE_DIR}/compat/vcbuild/vcpkg/downloads/tools/msys2/msys64/usr/bin/msgfmt.exe)
-		endif()
-		if(NOT EXISTS ${MSGFMT_EXE})
-			message(WARNING "Text Translations won't be built")
-			unset(MSGFMT_EXE)
-		endif()
+		message(WARNING "msgfmt not available and/or could not be installed, text translations won't be built.")
 	endif()
 endif()
 
@@ -1056,7 +1062,6 @@ set(NO_PYTHON )
 set(PAGER_ENV "LESS=FRX LV=-c")
 set(DC_SHA1 YesPlease)
 set(RUNTIME_PREFIX true)
-set(NO_GETTEXT )
 
 if(NOT CURL_FOUND)
 	set(NO_CURL 1)
@@ -1066,10 +1071,6 @@ if(NOT EXPAT_FOUND)
 	set(NO_EXPAT 1)
 endif()
 
-if(NOT Intl_FOUND)
-	set(NO_GETTEXT 1)
-endif()
-
 if(NOT PERL_TESTS)
 	set(NO_PERL 1)
 endif()