unit_integer_test - This test is used to determine the maximum integer size that
can be stored in a register, through the lense of the compiler. Possible values
are int16_t, int32_t, int64_t. This size is used by the instruction_cost_test as
reference size.

Usage:
Several compiler flags are required to get a meaningful result.
* flag to trigger emitting of assembly (-S for gcc)
* flag to enable optimizations in the compiler, so that it uses the available
  registers (-O for gcc), instead of loading/storing each value from memory.
* (possibly) flag to enable c99 standard (-std=c99 for gcc)

These flags need to be passed to the make file script in the CFLAGS variable.

The test is run as follows:
> cd unit_integer_test
> make CFLAGS="-O -std=c99 -S" test

If another compiler than the standard compiler (cc) should be used this compiler
can be passed in the CC variable.

> cd unit_integer_test
> make CFLAGS="-O -std=c99 -S" CC=gcc test


Result:
The last line of the make output and the file obj/result.txt will contain the
result size.

A run might look like the following.

> cd unit_integer_test
> make CFLAGS="-O -std=c99 -S" CC=gcc test
gcc -O -S src/test_fun_add_int16_t.c -o obj/int16_t.s
gcc -O -S src/test_fun_add_int32_t.c -o obj/int32_t.s
gcc -O -S src/test_fun_add_int64_t.c -o obj/int64_t.s
scripts/test.sh > obj/result.txt
cat obj/result.txt
int32_t
> 
