test-suite: set ROOT_INCLUDE_PATH if builddir is passed

Bug: https://github.com/vmc-project/geant4_vmc/pull/60

--- a/examples/test_suite.sh
+++ b/examples/test_suite.sh
@@ -193,8 +193,12 @@ fi
 
 # Set path to shared libraries if --builddir is provided via the option
 if [ "x${BUILDDIR}" != "x" ]; then
-  LIBS_FROM_BUILDDIR=$(find ${BUILDDIR} -iname "*.so" -exec dirname {} \; | tr '\r\n' ':')
+  LIBS_FROM_BUILDDIR=$(find ${BUILDDIR} -iname "*.so" -exec dirname {} \; | uniq | tr '\r\n' ':')
   export LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:${LIBS_FROM_BUILDDIR}
+  # In that case, also use headers from matching source dirs.
+  SOURCEDIR=$(readlink -f ../source/)
+  HEADERS_FROM_SOURCEDIR=$(find ${SOURCEDIR} -iname "*.h" -exec dirname {} \; | uniq | tr '\r\n' ':')
+  export ROOT_INCLUDE_PATH=${ROOT_INCLUDE_PATH}:${HEADERS_FROM_SOURCEDIR}
 fi
 
 # Create tmp dir from scratch