Disable the option to automatically inline functions by compiler to improve modding with tools

[SmileyAG]

Closes #3845

Yes, on the one hand, when using maximum optimization, automatic inline functions might be slightly affect performance, but at the same time it gives a huge problem to modders who used to make changes to each individual function using third-party tools (HLAE, bxt-rs, Orpheu, amxmodx and etc). So automatic inlines should be always disabled (unless if they are not forced in the code itself by the developer in the form of inline void e.g.).

@shawns-valve - these changes should also be applied to the engine as well, not just to game libraries!

-fno-inline: https://gcc.gnu.org/onlinedocs/gcc-5.4.0/gcc/Optimize-Options.html
OnlyExplicitInline (/Ob1): https://learn.microsoft.com/en-us/cpp/build/reference/ob-inline-function-expansion?view=msvc-170

[StevenKal]

Yeah, VALVe's devs should not change their compiler settings regarding this, because that will cause all hooking addons not anymore capable to catch a lot of functions for their plugins.
Knowing how many servers are using addons (very very huge %), consider this is a requirement.
Do not mess with our third-party addons modules/plugins (the ones usually dealing with memory hacking), however, we just do not want your updates... VALVe!