Make configure tests pass pickier compiler options.

Signed-off-by: Castor Fu <castor@alumni.caltech.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/configure b/configure
index 0f1acd0..2dda142 100755
--- a/configure
+++ b/configure
@@ -571,6 +571,7 @@
 linux_fallocate="no"
 cat > $TMPC << EOF
 #include <stdio.h>
+#include <fcntl.h>
 #include <linux/falloc.h>
 int main(int argc, char **argv)
 {
@@ -887,8 +888,7 @@
 #include <string.h>
 int main(int argc, char **argv)
 {
-  strcasestr(NULL, NULL);
-  return 0;
+  return strcasestr(argv[0], argv[1]) != NULL;
 }
 EOF
 if compile_prog "" "" "strcasestr"; then
@@ -902,6 +902,7 @@
 cat > $TMPC << EOF
 #include <unistd.h>
 #include <stdio.h>
+#include <getopt.h>
 int main(int argc, char **argv)
 {
   int c = getopt_long_only(argc, argv, NULL, NULL, NULL);
@@ -952,7 +953,7 @@
 tls_thread="no"
 cat > $TMPC << EOF
 #include <stdio.h>
-static int __thread ret;
+static __thread int ret;
 int main(int argc, char **argv)
 {
   return ret;