log4cxx: keeping in-source build (resolves #252)

This commit provides the autotools-brokensep class and uses it for
the log4cxx recipe.
The autotools-brokensep indicates that the log4cxx currently cannot
handle out-of-source builds, and hence the in-source build must be
kept until this is resolved.
The autotools-brokensep class is a copy of the autotools-brokensep
class provided in the openembedded-core commit 006b8a78 [1].
To make this commit backwards compatible to even earlier versions
of openembedded-core, we provide this class in meta-ros ourselves.

[1] http://cgit.openembedded.org/openembedded-core/commit/?id=006b8a7808a58713af16c326dc37d07765334b12

classes/autotools-brokensep.bbclass

+# Autotools class for recipes where separate build dir doesn't work
+# Ideally we should fix software so it does work. Standard autotools supports
+# this.
+inherit autotools
+B = "${S}"

recipes-devtools/log4cxx/log4cxx_0.10.0.bb

@@ -15,6 +15,6 @@ SRC_URI[sha256sum] = "0de0396220a9566a580166e66b39674cb40efd2176f52ad2c65486c99c
 
 S = "${WORKDIR}/apache-${BP}"
 
-inherit autotools pkgconfig
+inherit autotools-brokensep pkgconfig
 
 BBCLASSEXTEND += "native"