patch 9.0.1529: code style test doesn't check for space after "if"

Problem:    Code style test doesn't check for space after "if".
Solution:   Add a test for space.
diff --git a/src/os_win32.c b/src/os_win32.c
index c43a31a..869f02f 100644
--- a/src/os_win32.c
+++ b/src/os_win32.c
@@ -6863,7 +6863,7 @@
 	    vim_free(unicodebuf);
 	    unicodebuf = length ? LALLOC_MULT(WCHAR, length) : NULL;
 	    unibuflen = unibuflen ? 0 : length;
-	} while(1);
+	} while (TRUE);
 	cells = mb_string2cells(pchBuf, cbToWrite);
     }
     else // cbToWrite == 1 && *pchBuf == ' ' && enc_utf8