Make halide_assert() used in runtime more verbose.
Make halide_assert() used in runtime more verbose.

The message now includes the filename and line number that where the
assert was written and mentions that it is an assertion failure.

Not sure if this is the cleanest approach as two extra macros had to
be declared to handle __LINE__.


Former-commit-id: 8f9a58460d4ac58866a532702d7e208f8269303e
darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide