totalorder, totalorderf, totalorderl: new modules * lib/math.in.h: Declare totalorderf, totalorder, totalorderl. * lib/totalorder.c, lib/totalorderf.c, lib/totalorderl.c: * m4/totalorder.m4, modules/totalorder, modules/totalorder-tests: * modules/totalorderf, modules/totalorderf-tests: * modules/totalorderl, modules/totalorderl-tests: * tests/test-totalorder.c, tests/test-totalorderf.c: * tests/test-totalorderl.c: New files. * m4/math_h.m4 (gl_MATH_H, gl_MATH_H_REQUIRE_DEFAULTS) (gl_MATH_H_DEFAULTS): * modules/math (math.h): Set up totalorder, totalorderf, totalorderl. * m4/mathfunc.m4 (gl_MATHFUNC): Also support pointer-to-const.