clangd: include -std=c++98 in compile_commands.json

[SquareMan]

DTK parses the gc compiler c flags to convert them to equivalent clang flags for the purposes of generating a compile_commands.json file. However, it only recognized language flags if they're lowercase.

bfbb/tools/project.py

Lines 1628 to 1636 in 7ea69ef

	# Language configuration
	(
	"-lang",
	{
	"c": ("--language=c", "--std=c99"),
	"c99": ("--language=c", "--std=c99"),
	"c++": ("--language=c++", "--std=c++98"),
	"cplus": ("--language=c++", "--std=c++98"),
	},

This lowercases our -lang=c++ flag so that clangd will use the correct c++ version while analyzing the codebase.