gnu: Fix erroneous uses of 'package/inherit'.

gnu: Fix erroneous uses of 'package/inherit'.

These packages use a different source/version from the inherited package, and
thus should not inherit replacements.

* gnu/packages/check.scm (googletest-1.8, python-pytest-runner-2): Use record
inheritance instead of PACKAGE/INHERIT.
* gnu/packages/crates-io.scm (rust-bindgen-0.49, rust-bytes-0.4,
rust-colored-1.9.1, rust-difference-1, rust-docopt-0.8, rust-html5ever-0.23,
rust-http-0.1, rust-http-body-0.1, rust-loom-0.2, rust-loom-0.1,
rust-pulldown-cmark-0.0.8, rust-ring-0.13, rust-rustls-0.12, rust-sct-0.3,
rust-term-0.2, rust-untrusted-0.6, rust-webpki-0.18, rust-webpki-roots-0.17,
rust-webpki-roots-0.14): Likewise.
* gnu/packages/emacs.scm (emacs-next, emacs-next-pgtk, guile-emacs): Likewise.
* gnu/packages/guile.scm (guile-2.2.4): Likewise.
* gnu/packages/maths.scm (hdf5-1.10, hdf5-1.12): Likewise.
* gnu/packages/protobuf.scm (protobuf-3.6, protobuf-3.5, python-protobuf-3.6):
Likewise.
* gnu/packages/python-web.scm (python2-html2text): Likewise.
* gnu/packages/python-xyz.scm (python-pygments/fixed, python2-numpy,
python2-urwid, python2-markdown, python2-fonttools): Likewise.
* gnu/packages/racket.scm (racket): Likewise.
* gnu/packages/sequoia.scm (sequoia4pEp): Likewise.