[master] hack to check for previous isc/log directory

This is from patch ticket #1053 from jinmei.
http://bind10.isc.org/attachment/ticket/1053/makefile.diff

It is a workaround to problem with isc/log name reuse.

src/lib/python/isc/log/Makefile.am

@@ -23,6 +23,15 @@ log_la_LIBADD += $(PYTHON_LIB)
 # This is not installed, it helps locate the module during tests
 EXTRA_DIST = __init__.py
 
+# We're going to abuse install-data-local for a pre-install check.
+# This is to be considered a short term hack and is expected to be removed
+# in a near future version.
+install-data-local:
+	if test -d @pyexecdir@/isc/log; then \
+		echo "@pyexecdir@/isc/log is deprecated, and will confuse newer versions.  Please (re)move it by hand."; \
+		exit 1; \
+	fi
+
 pytest:
 	$(SHELL) tests/log_test