Replaced ASSERT function with a macro and enabled LTO

[tdulcet]

• Updated the ASSERT function to use a macro instead, similar to the C standard library assert macro in assert.h.
  • This should reduce the number of false positive warnings, as compilers and static analyzers can much more easily check if the assert is going to fail.
  • This should also result in a performance improvement, as it no longer needs to call a function to test the expression.
  • It seems to enable more loop unrolling, as evident by the required changes to the inline assembly. Thanks to @ldesnogu for help with that in Fixed assorted compiler warnings #22.
• Updated the makemake.sh script to enable Link Time Optimization (LTO) by default.

These ASSERT function changes were originally part of #22, but I had to remove them due it causing #10 on x86 systems when compiled with GCC:

INFO: Maximum recommended exponent for FFT length (3 Kdbl) = 66742; p[ = 66431]/pmax_rec = 0.9953402655.
Initial DWT-multipliers chain length = [hiacc] in carry step.
M66431: using FFT length 3K = 3072 8-byte floats, initial residue shift count = 16763
This gives an average   21.624674479166668 bits per digit
Using complex FFT radices        12         8        16
mers_mod_square: radix0/2 not exactly divisible by NTHREADS - This will hurt performance.
Using 4 threads in carry step
ERROR: Function mi64_shlc, at line 457 of file ../src/mi64.c
Assertion 'cy == 0ull' failed: Nonzero carryout of nonoverlapping vector add!

This should NOT be merged until after #10 is fixed.