isl_lp.c: make isl_tab_solve_lp static
isl_lp.c: make isl_tab_solve_lp static

This function has only ever been used locally.

Signed-off-by: Sven Verdoolaege <235c10dd23b819f81cdc9756a251746bc184cab6@gmail.com>

Meinersbur/isl,Meinersbur/isl,Meinersbur/isl,Meinersbur/isl