Include Systems Programming Optimizations

[bhuvy2]

Is your feature request related to a problem? Please describe.
As described in a reddit comment, we rely on non-standard and ambiguous behavior regularly. We should make note of that.

Describe the solution you'd like

1. The standard is inconsistent in a few places. When choosing between general and specific, compilers choose the most specific rule and when choosing between defined and undefined behavior, they’ll choose defined.
2. Non-Standard has many examples

• Absolute ordering of pointers in the case of malloc
• Pointer equality under different types
• Zero Length Arrays
• Callee Detection
• Constant Propagation
• Function Attributes
• Placement of variables in data sections (non portable)
• Variadic Macros
• Variable Length Arrays
• Compound literals for PTHREAD_MUTEX_INITIALIZER
  -noreturn is used in abort() and exit()
• Alignment
• Volatile Access for pthreads
• inline asm for memory barriers, mutex, system calls, etc etc
• Builtin Atomic Functions
• Thread local variables in errno

Describe alternatives you've considered
N/A

Additional context
N/A