add gobject to Requires: line

vips C and C++ programs can link directly against things in gobject
without appearing to, for example:

	a = VIPS_OBJECT( b );

the macro will expand to include a g_type_check_instance_is_a(). So we
have to have gobject-2.0 in the link line of things like:

	g++ -g -Wall hello8.cc `pkg-config vips-cpp --cflags --libs`

see also

	https://github.com/jcupitt/libvips/issues/196

ChangeLog

@@ -1,3 +1,6 @@
24/12/14 started 7.42.1
- add gobject-2.0 to Requires: in vips and vips-cpp .pc files

4/11/14 started 7.42.0
- better default resolution for png load
- better pbm (one bit) load, better pfm (float) load/save

configure.ac

@@ -2,7 +2,7 @@

# also update the version number in the m4 macros below

AC_INIT([vips], [7.42.0], [vipsip@jiscmail.ac.uk])
AC_INIT([vips], [7.42.1], [vipsip@jiscmail.ac.uk])
# required for gobject-introspection
AC_PREREQ(2.62)

@@ -18,7 +18,7 @@ AC_CONFIG_MACRO_DIR([m4])
# user-visible library versioning
m4_define([vips_major_version], [7])
m4_define([vips_minor_version], [42])
m4_define([vips_micro_version], [0])
m4_define([vips_micro_version], [1])
m4_define([vips_version],
          [vips_major_version.vips_minor_version.vips_micro_version])

vips-cpp.pc.in

@@ -6,5 +6,5 @@ includedir=@includedir@
Name: vips-cpp
Description: C++ API for vips8 image processing library
Version: @VERSION@
Requires: vips = @VERSION@
Requires: vips gobject-2.0
Libs: -L${libdir} -lvips-cpp

vips.pc.in

@@ -7,6 +7,7 @@ Name: vips
Description: Image processing library
Version: @VERSION@
Requires.private: @PACKAGES_USED@
Requires: gobject-2.0
Libs: -L${libdir} -lvips 
Libs.private: @EXTRA_LIBS_USED@
Cflags: -I${includedir}