Makefile: Use more variables to hold compiler flags
Enclose shell variables in quotes
Find missing preload libraries on non-english locales
Don't preload in subshell
Big overhaul

- Use constructor function attributes to find the originals of
   replaced symbols.
- Place scaffolding and support code in separate file(s).
- Measure clock ticks from (arbitrary) initial value.
- Write RIFF header for WAVE data.
- Provide wave data target as path or file descriptor number.
- Provide macros for wave generation parameters for easier
   customisation (e. g. by non-programmers).
QtCreator project
Improve source code documentation
Assume clock() always returns a valid result
Use full sample value range
Round integer division result to nearest
Refactor wave generation

- The new implementation requires no division to track sign
   changes.
Allow unsigned sample types (e. g. U8)
Makefile tracks changes in header file(s)
Allow 32-bit IEEE floating point samples
Ignore QtCreator project local file
Introduce thread-safety
Remove now unnecessary volatile qualifier

Since the static variable `inside_malloc' is now thread-local, it
cannot be modified in another thread outside the control of the current
thread. Therefore `volatile' is unnecessary.
tweaked writeWav to generate wav file with current timestamp