RFR: 7903936: Update variable names in build.sh documentation [v4]

[Oleksii Sylichenko]

> Changed variable name `CURL_OPTS` to `CURL_OPTIONS` in the documentation block "Some noteworthy control variables" in `build.sh`. 
> 
> `CURL_OPTIONS` is used in the `download_using_curl()` function in `build-support/build-common.sh`.

Oleksii Sylichenko has updated the pull request incrementally with two additional commits since the last revision:

 - Merge remote-tracking branch 'origin/fix-wget-options-variable' into fix-curl-error-options
 - Rename WGET_OPTS to WGET_OPTIONS in build.sh
   
   Changed variable name WGET_OPTS to WGET_OPTIONS in the documentation block "Some noteworthy control variables" in build.sh.
   
   WGET_OPTIONS is used in the download_using_wget() function in build-support/build-common.sh.

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

Changes:
  - all: https://git.openjdk.org/jtreg/pull/238/files
  - new: https://git.openjdk.org/jtreg/pull/238/files/a1c638f9..26d19213

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jtreg&pr=238&range=03
 - incr: https://webrevs.openjdk.org/?repo=jtreg&pr=238&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jtreg/pull/238.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/238/head:pull/238

PR: https://git.openjdk.org/jtreg/pull/238