RFR: 8320763: Fix spacing arround assignment in spec.gmk.in [v2]

[Magnus Ihse Bursie]

> For some reason, we have not been consistent with using spaces around the assignment operators (`:=` and `=`) in spec.gmk.in. This has annoyed me for a long time.
> 
> When making this change, I noticed that there are a lot of late evaluation assignments (= instead of :=) that should not be there. To not confuse the code review, I will fix these separately. Thus this change will only change whitespace.

Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:

  Fix ?=

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/16825/files
  - new: https://git.openjdk.org/jdk/pull/16825/files/d13fde56..e0ff03bb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16825&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16825&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/16825.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16825/head:pull/16825

PR: https://git.openjdk.org/jdk/pull/16825