Preprocessor constants should be preserved, not expanded

[deathcap]

The usage of the C preprocessor causes macro constants to expand in the transpiled output, undesirably. For example:

#include <stdio.h>

int main(int argc, char **argv) {
    exit(EXIT_FAILURE);
}

function main(argc, argv)
{
  exit(1);
}

would rather have exit(1) be exit(EXIT_FAILURE), possibly with a prior const EXIT_FAILURE = 1 definition.

[deathcap]

#define FOO 1 should transpile to const FOO = 1;, but #define foo(a,b) (a+b) to const foo = (a,b) => a + b;. Probably need a C preprocessor parser to do this, or somehow to interface with it, see GH-3.