Build with GOBJECT_INTROSPECTION=true can fail

[Milan Crha]

	Hi,
one reporter pointed me to a fact that you provide introspection
since 2.0.0. That sounds interesting, though the build can fail
when it is configured out of the source.

My steps:
a) cd libical-src
b) mkdir build
c) cd build
d) cmake -G "Unix Makefiles" -DGOBJECT_INTROSPECTION=true ..
e) make

The result is:

[ 21%] Linking C shared library ../../lib/libical.so
[ 25%] Built target ical
Scanning dependencies of target gir-girs
[ 26%] Generating libical-2.0.0.gir
In file included from /tmp/g-ir-cpp-fHTdLD.c:4:0:
..../libical-src/build/src/libical/ical.h:89:33: fatal error: libical_ical_export.h: No such file or directory
compilation terminated.
Caught exception: <class 'distutils.errors.CompileError'> CompileError(DistutilsExecError("command 'gcc' failed with exit status 1",),)
> /usr/lib64/python2.7/distutils/unixccompiler.py(121)preprocess()
-> raise CompileError, msg
(Pdb) 

Note that it ended in "(Pdb)" prompt, it didn't stop by usual means.
Only after I enter 'q' in the Pdb prompt I get the rest of the 'make'
run:

(Pdb) q
src/libical/CMakeFiles/gir-girs.dir/build.make:60: recipe for target 'src/libical/libical-2.0.0.gir' failed
make[2]: *** [src/libical/libical-2.0.0.gir] Error 1
CMakeFiles/Makefile2:228: recipe for target 'src/libical/CMakeFiles/gir-girs.dir/all' failed
make[1]: *** [src/libical/CMakeFiles/gir-girs.dir/all] Error 2
Makefile:138: recipe for target 'all' failed
make: *** [all] Error 2

	Bye,
	Milan