build: fix include paths in FreeBSD

FreeBSD package manager uses /usr/local/ as the default install path,
but that's not part of the compiler search path, so add it using the
APPEND_{LIB/INCLUDES} variables.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>

config/FreeBSD.mk

@@ -3,3 +3,7 @@ include $(XEN_ROOT)/config/StdGNU.mk
 # No wget on FreeBSD base system
 WGET = ftp
 PKG_INSTALLDIR = ${prefix}/libdata/pkgconfig
+
+# Add the default pkg install path
+APPEND_LIB += /usr/local/lib
+APPEND_INCLUDES += /usr/local/include