Link to ~/.guix-profile/lib/*.so

[Huang\, Ying]

I tried to build Linux kernel by hand with Guix.  But run `make
menuconfig` failed.  I checked the menuconfig program, found some
library couldn't be found.

$ ldd scripts/kconfig/mconf
        linux-vdso.so.1 (0x00007ffe87fe8000)
        libncursesw.so.6 => not found
        libgcc_s.so.1 => 
/gnu/store/vfvd0r69nv3221p907nb7cgk7inzmf9q-gcc-6.3.0-lib/lib/libgcc_s.so.1 
(0x00007fd7fd492000)
        libc.so.6 => 
/gnu/store/iwgi9001dmmihrjg4rqhd6pa6788prjw-glibc-2.24/lib/libc.so.6 
(0x00007fd7fd0f3000)
        
/gnu/store/iwgi9001dmmihrjg4rqhd6pa6788prjw-glibc-2.24/lib/ld-linux-x86-64.so.2 
(0x00007fd7fd6a9000)

$ ls ~/.guix-profile/lib/libncursesw.so.6
/home/<user>/.guix-profile/lib/libncursesw.so.6@

Set LD_LIBRARY_PATH=$HOME/.guix-profile/lib could solve this, but it is
said that is not a good solution.  So I think we need a solution to make
$HOME/.guix-profile/lib the fallback to search dynamic linked library.

Best Regards,
Huang, Ying