pdh: Fixed wrong condition.

dlls/pdh/pdh_main.c

diff --git a/dlls/pdh/pdh_main.c b/dlls/pdh/pdh_main.c
index a7aa21b..d78af4a 100644
--- a/dlls/pdh/pdh_main.c
+++ b/dlls/pdh/pdh_main.c
@@ -873,7 +873,7 @@
         return PDH_CSTATUS_NO_MACHINE;
     }
 
-    if (!buffer && !size) return PDH_INVALID_ARGUMENT;
+    if (!buffer || !size) return PDH_INVALID_ARGUMENT;
     if (!index) return ERROR_SUCCESS;
 
     for (i = 0; i < sizeof(counter_sources) / sizeof(counter_sources[0]); i++)