Fixing compilation issues with external example

[hkaiser]

• also: fix documentation (remove stubs, remove mentioning of ini files)
• this fixes Compilation error while running sample hello_world_component code #2011 and pkg-config order incorrect on 14.04 / GCC 4.8 #2009

[hkaiser]

@satyaki3794: Could you please verify whether this fixes your problem?

[satyaki3794]

The directory hpx/examples/hello_world_component has hello.sh which contains the commands needed to build and run this example. I am not sure about this but I think some of the commands in that file are incorrect/incomplete. Compilation fails at the first step, while generating the .so file, which can be fixed by adding the -fPIC flag.

After that has been fixed, when I run ./hello.sh, I get the following compilation errors. http://pastebin.com/crgQsFwy.

Maybe, like this issue (#2009), the pkgconfig order in the .pc file is incorrect here too. I tried permuting the order of binaries like zao had done in the above case but to no avail.

[hkaiser]

Compilation fails at the first step, while generating the .so file, which can be fixed by adding the -fPIC flag.

I now added the -fPIC to the pkgcfg options. I also tried to compile it again, seems to work now.

[satyaki3794]

I built the 'fixing_2011' branch and ran hello.sh in hpx/examples/hello_world_component. I got the same compilation errors yet again (http://pastebin.com/C5HeFxtB). As the errors were regarding undefined references (to hpx::cout, write_async() etc.), I searched online and found a similar issue (#268).

The c++ command to run hello_world_client.cpp after generating the .so file, has the -lhpx_iostreams flag, and my LD_LIBRARY_PATH environment variable points to $HPX_INSTALL_LOCATION/lib. I am on Ubuntu 14.04 with gcc 4.8.2.
I tried moving around the -lhpx_iostreams flag in the command but wasn't able to resolve it.

[hkaiser]

@satyaki3794 I changed the pkgcfg files such that the HPX libraries are referenced by full file name. As outlined in #2009, this should at least fix that first issue you reported. I'm still not clear why you see those hpx::cout et.al. as missing symbols. They should be defined in libhpx_iostreams.so (could you verify whether they are defined there?).

[satyaki3794]

Please move the -lhpx_iostreams flag to the end of the command while compiling hello_world_client.cpp. It resolves the compilation errors.

[satyaki3794]

I built and tested the changes. Everything is working as expected.