Failure to build firefox

[Paul Goyette <paul%whooppee.com@localhost>]

With an up-to-date pkgsrc, and starting with a newly created sandbox 
(via sysutils/mksandbox), I am seeing the following errors:

/tmp/pkgs/www/firefox/work.x86_64/firefox-63.0.3/js/src/wasm/AsmJS.cpp: In function 'bool js::CompileAsmJS(JSContext*, js::AsmJSParser&, js::frontend::ParseNode*, bool*)':
/tmp/pkgs/www/firefox/work.x86_64/firefox-63.0.3/js/src/wasm/AsmJS.cpp:6750:76: warning: 'time' may be used uninitialized in this function [-Wmaybe-uninitialized]
     return JS_smprintf("total compilation time %dms; %s", time, cacheString);
                                                                            ^
/tmp/pkgs/www/firefox/work.x86_64/firefox-63.0.3/js/src/wasm/AsmJS.cpp:6778:18: note: 'time' was declared here
         unsigned time;
                  ^~~~



+------------------+--------------------------+----------------------------+
| Paul Goyette     | PGP Key fingerprint:     | E-mail addresses:          |
| (Retired)        | FA29 0E3B 35AF E8AE 6651 | paul at whooppee dot com   |
| Kernel Developer | 0786 F758 55DE 53BA 7731 | pgoyette at netbsd dot org |
+------------------+--------------------------+----------------------------+