[SOL] Optimize rustlib for size

[LucasSte]

When we enable ALU32 with SBPFv2 and SBPFv3, rustc starts inlining more functions than before, since they may be smaller. Such aggressive inning increases program size.

Building the rust lib with the "s" option prevents inlining and loop unrolling.

rust/config.example.toml

Lines 429 to 443 in 08b7341

	# Whether or not to optimize when compiling the compiler and standard library,
	# and what level of optimization to use.
	# WARNING: Building with optimize = false is NOT SUPPORTED. Due to bootstrapping,
	# building without optimizations takes much longer than optimizing. Further, some platforms
	# fail to build without this optimization (c.f. #65352).
	# The valid options are:
	# true - Enable optimizations.
	# false - Disable optimizations.
	# 0 - Disable optimizations.
	# 1 - Basic optimizations.
	# 2 - Some optimizations.
	# 3 - All optimizations.
	# "s" - Optimize for binary size.
	# "z" - Optimize for binary size, but also turn off loop vectorization.
	#optimize = true