* gl_rasterizer_cache: Mark file-scope functions as static where applicable
Prevents -Wmissing-declaration warnings from occurring and also makes
these functions internally linked.
* gl_rasterizer_cache: Remove unused local std::string variable
Despite being unused, compilers are unable to completely remove any code
gen related to the construction and destruction of this variable, since
the destructor of std::string is non-trivial.
Thus, we can remove it to reduce a minor amount of unnecessary code
generation
* gl_rasterizer_cache: Mark hash implementation as noexcept
This shouldn't throw.
* gl_rasterizer_cache: Remove unused variable in ClearAll()
* gl_rasterizer_cache: Make use of const on references explicit
While declared as auto&, these actually behave as const auto& variables,
due to the constness of the container being iterated. We can make this
explicit for readability sake.
* gl_rasterizer_cache: Resolve truncation warnings
The size is forwarded to a std::memset call, which takes a std::size_t
as its size parameter, so we can just make this change to silence the
warnings.
* gl_rasterizer_cache: Resolve variable shadowing warnings
Prevents a -Wshadow warning from occurring.