Revert "libmicrohttpd: update to 0.9.51"

This reverts commit 48073884101fe3db7d4bfc8d0b585232bd0e9080.

The commit broke the build with the pre-built Blackfin toolchain.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/libmicrohttpd/libmicrohttpd.hash

@@ -1,2 +1,2 @@
 # Locally calculated
-sha256	3000bb0ba219061f2ea60251b8ea3d5f694e8c6ce1706bbff57e7e24867a23c7	libmicrohttpd-0.9.51.tar.gz
+sha256	d1b6385068abded29b6470e383287aa7705de05ae3c08ad0bf5747ac4dc6ebd7	libmicrohttpd-0.9.50.tar.gz

package/libmicrohttpd/libmicrohttpd.mk

@@ -4,18 +4,18 @@
 #
 ################################################################################
 
-LIBMICROHTTPD_VERSION = 0.9.51
+LIBMICROHTTPD_VERSION = 0.9.50
 LIBMICROHTTPD_SITE = $(BR2_GNU_MIRROR)/libmicrohttpd
 LIBMICROHTTPD_LICENSE_FILES = COPYING
 LIBMICROHTTPD_INSTALL_STAGING = YES
 LIBMICROHTTPD_CONF_OPTS = --disable-curl --disable-examples
 LIBMICROHTTPD_CFLAGS = $(TARGET_CFLAGS) -std=c99
 
-# gcc on arc doesn't define _REENTRANT when -pthread is
+# gcc on arc and bfin doesn't define _REENTRANT when -pthread is
 # passed while it should. Compensate this defiency here otherwise
 # libmicrohttpd configure script doesn't find that thread support is
 # enabled.
-ifeq ($(BR2_arc),y)
+ifeq ($(BR2_arc)$(BR2_bfin),y)
 LIBMICROHTTPD_CFLAGS += -D_REENTRANT
 endif