www/nift: Update to 2.3.9

From ChangeLog (https://github.com/nifty-site-manager/nsm/releases/tag/v2.3.9):

• added exprtk_disable_caseinsensitivity for ExprTk
• merged PR from Mamadou fixing support for compiling with Lua 5.2 and 5.1
• added !mf option to definitions
• added in types std::vector<double> and std::vector<string>
• added in std::vector. fns at, erase, pop_back, push_back, set, size (also member fns)
• added in stream. fns close, open (also member fns)
• added in exprtk.compile, exprtk.eval, exprtk.load and exprtk.str fns for f++/n++
• added in exprtk_compile, exprtk_eval, exprtk_load and exprtk_str fns for Lua
• added in to_string fn for ExprTk
• fixed so that fn name/options/params are parsed with f++ always
• fixed various bugs
• made various improvements

PR: 246489
Submitted by: info@babaei.net (maintainer)