Convert GETMNTINFO_USES_STATVFS check to CMake

Fix to build on such platforms, it is used but not checked with CMake.

CMakeLists.txt

@@ -352,6 +352,17 @@ if( ${CMAKE_SYSTEM_NAME} STREQUAL "OpenBSD" )
 endif( )
 
 check_function_exists( getmntinfo HAVE_GETMNTINFO )
+if( HAVE_GETMNTINFO )
+  check_cxx_source_compiles("
+    #include <sys/types.h>
+    #include <sys/statvfs.h>
+    int main(){
+      struct statvfs *mntbufp;
+      int flags;
+      return getmntinfo(&mntbufp, flags);
+    }"
+    GETMNTINFO_USES_STATVFS )
+endif( HAVE_GETMNTINFO )
 check_function_exists( getnameinfo HAVE_GETNAMEINFO )
 check_function_exists( getpagesize HAVE_GETPAGESIZE )
 check_function_exists( getpeereid HAVE_GETPEEREID )

config.h.cmake

@@ -24,7 +24,7 @@
 #undef GETADDRINFO_RETURNS_UNIX
 
 /* getmntinfo() uses struct statvfs */
-#undef GETMNTINFO_USES_STATVFS
+#cmakedefine GETMNTINFO_USES_STATVFS
 
 /* Define if you have the MIT Kerberos libraries */
 #undef GSSAPI_MIT