MSVC: compat: implement setenv()
diff --git a/CMakeModules/UseCompat.cmake b/CMakeModules/UseCompat.cmake
index eb4b103..08c29a2 100644
--- a/CMakeModules/UseCompat.cmake
+++ b/CMakeModules/UseCompat.cmake
@@ -56,6 +56,7 @@
     check_symbol_exists(strptime "time.h" HAVE_STRPTIME)
     check_symbol_exists(mmap "sys/mman.h" HAVE_MMAP)
     check_symbol_exists(dirname "libgen.h" HAVE_DIRNAME)
+    check_symbol_exists(setenv "stdlib.h" HAVE_SETENV)
 
     unset(CMAKE_REQUIRED_DEFINITIONS)
     unset(CMAKE_REQUIRED_LIBRARIES)