lang/njs: update 0.7.4 -> 0.7.5

<ChangeLog>

nginx modules:

*) Change: adapting to changes in nginx header structures.

*) Bugfix: fixed r.headersOut special getters when value

is absent.

*) Change: returning undefined value instead of an empty string

for Content-Type when the header is absent.

Core:

*) Bugfix: fixed catching of the exception thrown from an

awaited function.

*) Bugfix: fixed function value initialization.

*) Bugfix: fixed interpreter when await fails.

*) Bugfix: fixed typed-array constructor when source array

is changed while iterating.

*) Bugfix: fixed String.prototype.replace() with byte strings.

*) Bugfix: fixed template literal from producing byte-strings.

*) Bugfix: fixed array iterator with sparse arrays.

*) Bugfix: fixed memory free while converting a flat array to

a slow array.

*) Bugfix: properly handling NJS_DECLINE in promise native

functions.

*) Bugfix: fixed working with an array-like object in Promise.all()

and friends.

</ChangeLog>