cmake: Always check for strtoull

This fixes building with different compilers on Windows

BUG: https://red.libssh.org/issues/225

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>

ConfigureChecks.cmake

@@ -124,6 +124,7 @@ endif (NOT WITH_GCRYPT)
 
 check_function_exists(isblank HAVE_ISBLANK)
 check_function_exists(strncpy HAVE_STRNCPY)
+check_function_exists(strtoull HAVE_STRTOULL)
 
 if (NOT WIN32)
   check_function_exists(vsnprintf HAVE_VSNPRINTF)
@@ -190,7 +191,6 @@ if (UNIX)
 
     check_library_exists(util forkpty "" HAVE_LIBUTIL)
     check_function_exists(cfmakeraw HAVE_CFMAKERAW)
-    check_function_exists(strtoull HAVE_STRTOULL)
     check_function_exists(__strtoull HAVE___STRTOULL)
 endif (UNIX)