Fix compilation flag typo in Makefile
Clean up warnings

Now that -pedantic is actually active (oops: GCC never complained
about it being misspelled), clean up several newly uncovered
warnings.

Apply the noreturn attribute to the die functions so the compiler
knows that execution will not continue. This fixes several "variable
is used uninitialized" warnings.

Specify C99 to allow declaration after statement.

Use an explicit "return;" instead of returning the "result" of
a void function.

Explicitly cast the dlsym result to a function pointer.

  GCC still "rightly" complains about the conversions from object
  pointer to function pointer under -pedantic, but this at least
  seems to silence Clang.

The result compiles cleanly with clang from Xcode 4.6; GCC's only
remaining warnings are for the object pointer to function pointer
conversions.