build: allow configure and build in a separate directory
Some .h files in lib/ are autogenerated. The search path should
include the build directory and the source directory. They usually
match but sometimes, they may be different. For example:
$ mkdir build
$ cd build
$ ../configure
$ make
diff --git a/lib/Makefile.am b/lib/Makefile.am
index 890cc5c..4c67858 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -1,6 +1,6 @@
## Process this file with automake to produce Makefile.in.
-INCLUDES = @INCLUDES@ -I.. -I$(top_srcdir) -I$(top_srcdir)/lib @SNMP_INCLUDES@
+INCLUDES = @INCLUDES@ -I.. -I$(top_srcdir) -I$(top_srcdir)/lib -I$(top_builddir)/lib @SNMP_INCLUDES@
DEFS = @DEFS@ -DSYSCONFDIR=\"$(sysconfdir)/\"
lib_LTLIBRARIES = libzebra.la