Merge remote-tracking branch 'qatar/release/0.7' into release/0.8

* qatar/release/0.7:
  configure: add missing CFLAGS to fix building on the HURD

Merged-by: Michael Niedermayer <michaelni@gmx.at>

configure

@@ -2537,6 +2537,7 @@ case $target_os in
         add_cppflags -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600 -D_BSD_SOURCE
         ;;
     gnu)
+        add_cppflags -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600
         ;;
     qnx)
         add_cppflags -D_QNX_SOURCE