ftplugin/spec.vim: Revert change dropping <SID> from SpecChangelog

[bcl]

Without this it will return an error when creating a new changelog
entry:
"Unknown function: SpecChangelog"

[k-takata]

Have you tried contacting the maintainer?

[brammool]

@ignatenkobrain

[Jakuje]

Verified that this solves my issue that I had last couple of weeks.

[codecov]

Codecov Report

Merging #9032 (61d3ac3) into master (94e7d34) will decrease coverage by 0.04%.
The diff coverage is n/a.

❗ Current head 61d3ac3 differs from pull request most recent head a403350. Consider uploading reports for the commit a403350 to get more accurate results

@@            Coverage Diff             @@
##           master    #9032      +/-   ##
==========================================
- Coverage   90.09%   90.04%   -0.05%     
==========================================
  Files         151      147       -4     
  Lines      169614   167890    -1724     
==========================================
- Hits       152807   151175    -1632     
+ Misses      16807    16715      -92     

Flag	Coverage Δ
huge-clang-none	?
huge-gcc-none	89.70% <ø> (+<0.01%)	⬆️
huge-gcc-testgui	88.35% <ø> (+0.01%)	⬆️
huge-gcc-unittests	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/libvterm/src/unicode.c	70.83% <0.00%> (-18.75%)	⬇️
src/json.c	91.55% <0.00%> (-1.14%)	⬇️
src/help.c	89.76% <0.00%> (-1.08%)	⬇️
src/sound.c	96.03% <0.00%> (-1.00%)	⬇️
src/if_xcmdsrv.c	88.86% <0.00%> (-0.93%)	⬇️
src/strings.c	95.99% <0.00%> (-0.55%)	⬇️
src/beval.c	82.81% <0.00%> (-0.53%)	⬇️
src/message.c	88.19% <0.00%> (-0.44%)	⬇️
src/clipboard.c	83.35% <0.00%> (-0.44%)	⬇️
src/syntax.c	86.58% <0.00%> (-0.43%)	⬇️
... and 54 more

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[zdohnal]

This PR is partially fixed in Vim project - it is only missing a downstream patch from Fedora
vim-7.4-releasestring-1318991.patch.txt

I've sent the fix to @ignatenkobrain via email as well.