buildroot using external toolchain – rootfilesystem creating

I am trying to build my own rootfile system for RPI using buildroot.
I am new to buildroot.

I have downloaded following cross compiler folder from git :–
as mentioned in this link :–

How i will come to know what is the kernel header is used by above cross compiler ?

My installer GCC compiler is :–

crosscompiler is downloaded from git at following location:–

Please suggest what value to fill here for toolchain selection :–

Toolchain type : External toolchain
Toolchain : Custom toolchain
Toolchain origin : Pre-installed toolchain
Toolchain path : ?
Toolchain prefix : ?
external Toolchain kernel header series : ?
external toolchain c library : ?

Cross compiler not finding SDL package

i am cross compiling a small application which uses libsdl (SDL). I can compile using gcc but not able to with cross compiler. the cross compiler i am using is arm-arago-linux-gnueabi-gcc. error message come as

/arm-arago-linux-gnueabi/bin/ld: cannot find -lSDL
although libsdl1.2-dev is installed an i am getting pkg-config –cflags sdl output as -D_GNU_SOURCE=1 -D_REENTRANT -I/usr/include/SDL
and output of pkg-config –libs sdl as -lSDL.
Since my native compiler gcc is detecting SDL libs any idea why my cross compiler not able to find the libraries