lttng-babeltrace: fix static build again

I accidentally removed the static build patch when bumping to v1.4.0,
thinking it was merged upstream as of this version, but it's not the
case (it's merged in master), so let's keep the patch file.

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

package/lttng-babeltrace/0003-fix-uuid-support-detection-on-static-build.patch

@@ -0,0 +1,86 @@
+From 2741f55be80ae8af169ae795ea28d2a39c18fa60 Mon Sep 17 00:00:00 2001
+From: Samuel Martin <s.martin49@gmail.com>
+Date: Wed, 1 Jun 2016 21:56:32 +0200
+Subject: [PATCH] configure: fix uuid support detection on static build
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This change adds uuid detection using pkg-config helper before falling
+back on the standard AC_CHECK_LIB detection for platforms missing
+pkg-config.
+
+AC_CHECK_LIB function achieves its test by trying to link against the
+requested library, without taking care of its dependency
+requirements/flags that may differ between different targets.
+Therefore, in case of static build, it can fail on the uuid detection
+like [1], because the uuid's dependency flags (regarding gettext) are
+missing.
+
+Instead, using pkg-config to do the check will take care of getting and
+setting all required flags.
+
+This issue [1] has been triggered on Buildroot farms.
+
+[1] http://autobuild.buildroot.net/results/43b/43b98ddf9eb44152ed9ac4a98d887af14831d8da/build-end.log
+
+Signed-off-by: Samuel Martin <s.martin49@gmail.com>
+Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
+[Philippe: grabbed from this upstream patch:
+    https://github.com/efficios/babeltrace/commit/2741f55be80ae8af169ae795ea28d2a39c18fa60.patch
+]
+Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
+---
+ configure.ac | 31 +++++++++++++++++++++----------
+ 1 file changed, 21 insertions(+), 10 deletions(-)
+
+diff --git a/configure.ac b/configure.ac
+index 84f9000..2f5e3f8 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -163,24 +163,35 @@ AC_CHECK_FUNCS([uuid_generate],
+   link_with_libuuid=no
+ ],
+ [
+-  # Check for libuuid
+-  AC_CHECK_LIB([uuid], [uuid_generate],
++  # First, check the pkg-config module is available, otherwise explicitly check
++  # for libuuid, or uuid support in the C-library.
++  PKG_CHECK_MODULES([UUID], [uuid],
+   [
++    LIBS="${UUID_LIBS} ${LIBS}"
++    CFLAGS="${CFLAGS} ${UUID_CFLAGS}"
+     AC_DEFINE_UNQUOTED([BABELTRACE_HAVE_LIBUUID], 1, [Has libuuid support.])
+     link_with_libuuid=yes
+   ],
+   [
+-    # libuuid not found, check for uuid_create in libc.
+-    AC_CHECK_LIB([c], [uuid_create],
++    # Check for libuuid
++    AC_CHECK_LIB([uuid], [uuid_generate],
+     [
+-      AC_DEFINE_UNQUOTED([BABELTRACE_HAVE_LIBC_UUID], 1, [Has libc uuid support.])
+-      link_with_libc_uuid=yes
++      AC_DEFINE_UNQUOTED([BABELTRACE_HAVE_LIBUUID], 1, [Has libuuid support.])
++      link_with_libuuid=yes
+     ],
+     [
+-      # for MinGW32 we have our own internal implemenation of uuid using Windows functions.
+-      if test "x$MINGW32" = xno; then
+-        AC_MSG_ERROR([Cannot find libuuid uuid_generate nor libc uuid_create. Use [LDFLAGS]=-Ldir to specify their location.])
+-      fi
++      # libuuid not found, check for uuid_create in libc.
++      AC_CHECK_LIB([c], [uuid_create],
++      [
++        AC_DEFINE_UNQUOTED([BABELTRACE_HAVE_LIBC_UUID], 1, [Has libc uuid support.])
++        link_with_libc_uuid=yes
++      ],
++      [
++        # for MinGW32 we have our own internal implemenation of uuid using Windows functions.
++        if test "x$MINGW32" = xno; then
++          AC_MSG_ERROR([Cannot find libuuid uuid_generate nor libc uuid_create. Use [LDFLAGS]=-Ldir to specify their location.])
++        fi
++      ])
+     ])
+   ])
+ ])

package/lttng-babeltrace/lttng-babeltrace.mk

@@ -14,7 +14,9 @@ HOST_LTTNG_BABELTRACE_DEPENDENCIES = \
 	host-popt host-util-linux host-libglib2 host-pkgconf
 HOST_LTTNG_BABELTRACE_CONF_OPTS += --disable-debug-info
 
-# For 0002-m4-ax_lib_elfutils.m4-add-cache-variable.patch
+# For:
+#   0002-m4-ax_lib_elfutils.m4-add-cache-variable.patch
+#   0003-fix-uuid-support-detection-on-static-build.patch
 LTTNG_BABELTRACE_AUTORECONF = YES
 
 ifeq ($(BR2_PACKAGE_ELFUTILS),y)