configure.ac: fix botched FREAD_READS_DIRECTORIES check

3adf9fd (configure.ac: loosen FREAD_READS_DIRECTORIES test program,
2017-06-14) broke the test program for the FREAD_READS_DIRECTORIES check
by making it syntactically invalid (a dangling ")") and by botching the
type returned from 'main' (a FILE* rather than int). As a consequence,
the test program won't even compile, thus the check fails
unconditionally. Fix these problems.

Reported-by: Jonathan Primrose <[email protected]>
Signed-off-by: Eric Sunshine <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: sunshineco

configure.ac

@@ -867,7 +867,7 @@ AC_RUN_IFELSE(
 	[AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT],
 		[[
 		FILE *f = fopen(".", "r");
-		return f)]])],
+		return f != NULL;]])],
 	[ac_cv_fread_reads_directories=no],
 	[ac_cv_fread_reads_directories=yes])
 ])