MSVC build fix & buildsystem overhaul

ext/ultragetopt/CMakeLists.txt

@@ -0,0 +1,22 @@
+include(CheckIncludeFile)
+include(CheckFunctionExists)
+
+check_include_file(strings.h HAVE_STRINGS_H)
+check_function_exists(strcasecmp HAVE_STRCASECMP)
+check_function_exists(_stricmp HAVE__STRICMP)
+check_function_exists(strncasecmp HAVE_STRNCASECMP)
+check_function_exists(_strnicmp HAVE__STRNICMP)
+
+add_library(ultragetopt
+	ultragetopt.c ultragetopt.h)
+add_library(External::ultragetopt ALIAS ultragetopt)
+
+target_include_directories(ultragetopt
+	PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+
+target_compile_definitions(ultragetopt PRIVATE
+	$<$<BOOL:${HAVE_STRINGS_H}>:HAVE_STRINGS_H=1>
+	$<$<BOOL:${HAVE_STRCASECMP}>:HAVE_STRCASECMP=1>
+	$<$<BOOL:${HAVE__STRICMP}>:HAVE__STRICMP=1>
+	$<$<BOOL:${HAVE_STRNCASECMP}>:HAVE_STRNCASECMP=1>
+	$<$<BOOL:${HAVE__STRNICMP}>:HAVE__STRNICMP=1>)