fastrtps: fix tinyxml2 library search

* fixes rmw-fastrtps-cpp failure:
  http://errors.yoctoproject.org/Errors/Details/174717/

  DEBUG: Executing shell function do_compile
  NOTE: VERBOSE=1 cmake --build TOPDIR/tmp-glibc/work/aarch64-oe-linux/rmw-fastrtps-cpp/git-r0/build --target all -- -j 9
  ninja: error: 'TOPDIR/tmp-glibc/work/aarch64-oe-linux/fastrtps/git-r0/recipe-sysroot/usr/lib/libtinyxml2.so', needed by 'librmw_fastrtps_cpp.so', missing and no known rule to make it
  WARNING: TOPDIR/tmp-glibc/work/aarch64-oe-linux/rmw-fastrtps-cpp/git-r0/temp/run.do_compile.13110:1 exit 1 from 'eval ${DESTDIR:+DESTDIR=${DESTDIR} }VERBOSE=1 cmake --build 'TOPDIR/tmp-glibc/work/aarch64-oe-linux/rmw-fastrtps-cpp/git-r0/build' "$@" -- -j 9'
  ERROR: Function failed: do_compile (log file is located at TOPDIR/tmp-glibc/work/aarch64-oe-linux/rmw-fastrtps-cpp/git-r0/temp/log.do_compile.13110)

* it was caused by fastrtps's /usr/lib/fastrtps/cmake/fastrtpsTargets.cmake
  containing the full path to libtinyxml2.so inside fastrtps's WORKDIR
  which might be already removed by rm_work by the time when
  rmw-fastrtps-cpp is being built

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

recipes-ros2/fastrtps/fastrtps/0001-FindTinyXML2-use-pkg-config-to-find-tinyxml2.patch

@@ -0,0 +1,46 @@
+From 50fbc5f526cea5f7dab554deb2a9256bddf8d0cc Mon Sep 17 00:00:00 2001
+From: Martin Jansa <Martin.Jansa@gmail.com>
+Date: Tue, 10 Apr 2018 08:40:05 +0000
+Subject: [PATCH] FindTinyXML2: use pkg-config to find tinyxml2
+
+* otherwise it finds the whole path to RSS inside fastrtps and then uses
+  it in fastrtpsTargets.cmake which brakes users of this (e.g. rmw-fastrtps-cpp)
+  when they are built after fastrtps WORKDIR was already removed (e.g. with rm-work)
+
+  fastrtps/git-r0 $ grep -B 1 -A 1 work  image/usr/lib/fastrtps/cmake/fastrtpsTargets.cmake
+  set_target_properties(fastrtps PROPERTIES
+    INTERFACE_LINK_LIBRARIES "-lpthread;/OE/build/oe-core/tmp-glibc/work/aarch64-oe-linux/fastrtps/git-r0/recipe-sysroot/usr/lib/libtinyxml2.so"
+  )
+
+Upstream-Status: Pending
+
+Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
+---
+ cmake/modules/FindTinyXML2.cmake | 10 +++-------
+ 1 file changed, 3 insertions(+), 7 deletions(-)
+
+diff --git a/cmake/modules/FindTinyXML2.cmake b/cmake/modules/FindTinyXML2.cmake
+index 24aa98a..bdb426a 100644
+--- a/cmake/modules/FindTinyXML2.cmake
++++ b/cmake/modules/FindTinyXML2.cmake
+@@ -4,14 +4,10 @@
+ 
+ option(TINYXML2_FROM_SOURCE "Integrate TinyXML2 source code inside Fast RTPS" OFF)
+ 
+-find_package(TinyXML2 CONFIG QUIET)
++find_package(PkgConfig)
++pkg_check_modules(TinyXML2 REQUIRED tinyxml2)
+ if(TinyXML2_FOUND)
+-    message(STATUS "Found TinyXML2: ${TinyXML2_DIR}")
+-    if(NOT TINYXML2_LIBRARY AND TARGET tinyxml2)
+-        # in this case, we're probably using TinyXML2 version 5.0.0 or greater
+-        # in which case tinyxml2 is an exported target and we should use that
+-        set(TINYXML2_LIBRARY tinyxml2)
+-    endif()
++    set(TINYXML2_LIBRARY ${TinyXML2_LIBRARIES})
+ else()
+     if(THIRDPARTY)
+         set(TINYXML2_FROM_SOURCE ON)
+-- 
+2.7.6
+

recipes-ros2/fastrtps/fastrtps_git.bb

@@ -7,7 +7,8 @@ DEPENDS = "asio libtinyxml2"
 SRCREV = "e49bbe6a18fbff509097fb3d2e0d18648e94f7c1"
 SRC_URI = "git://github.com/eProsima/Fast-RTPS.git;protocol=git; \
     file://0001-don-t-use-INSTALL_INTERFACE.patch \
-           "
+    file://0001-FindTinyXML2-use-pkg-config-to-find-tinyxml2.patch \
+"
 
 S = "${WORKDIR}/git"