Update sprintf.js library from 1.0.2 to 1.1.2.

Includes a changeset that removes a SpiderMonkey segfault from occurring (when passing an XmppClient JS::Heap or JS::PersistentRooted GUIMessage following rP22856), refs #5636.
https://bugzilla.mozilla.org/show_bug.cgi?id=1234425
https://bugzilla.mozilla.org/show_bug.cgi?id=1238475
https://github.com/alexei/sprintf.js/commit/61c795624204883948c0e19f8af208f5359e6fdb

sprintf.js commits that add new features:

padding (intent) support:
https://github.com/alexei/sprintf.js/commit/9e846915e273ebeb12b4decc59af94d596e5ee92

Adds support for the %g placeholder
g — yields a float as is; see notes on precision above
https://github.com/alexei/sprintf.js/commit/a60a5705fcb589b55373b1f15f2b4b5b5892f19c

Adds type option
T — yields the type of the argument1
https://github.com/alexei/sprintf.js/commit/c31c24ecefe92abff04fc38f860ad50c97bebf62

Adds support for the %t (boolean) type specifier
t — yields true or false
https://github.com/alexei/sprintf.js/commit/b92b530c7a4c6ef98632339e05cdea8a041da857

Adds support for returning primitive values through the %v specifier
v — yields the primitive value of the specified argument
https://github.com/alexei/sprintf.js/commit/f18037240bbbc7d53ede6be9a1d7bc964a75e309

The other commits clean sprintf internals and do not change the existing formats, see:
https://github.com/alexei/sprintf.js/blob/1.0.2/src/sprintf.js
https://github.com/alexei/sprintf.js/blob/1.1.2/src/sprintf.js
https://github.com/alexei/sprintf.js/blob/1.1.2/README.md

Differential Revision: https://code.wildfiregames.com/D2421
Tested by: Angen