fix small bug in VariantContextBuilder

[yfarjoun]

• clean up braces while I'm at it.

Description

Please explain the changes you made here. Explain the motivation for making this change. What existing problem does the pull request solve?

Things to think about before submitting:

• [ ] Make sure your changes compile and new tests pass locally.
• [ ] Add new tests or update existing ones:
  • A bug fix should include a test that previously would have failed and passes now.
  • New features should come with new tests that exercise and validate the new functionality.
• [ ] Extended the README / documentation, if necessary
• [ ] Check your code style.
• [ ] Write a clear commit title and message
  • The commit message should describe what changed and is targeted at htsjdk developers
  • Breaking changes should be mentioned in the commit message.

[codecov-io]

Codecov Report

Merging #1403 into master will increase coverage by 0.003%. The diff coverage is 84.091%.

@@               Coverage Diff               @@
##              master     #1403       +/-   ##
===============================================
+ Coverage     68.116%   68.118%   +0.003%     
  Complexity      8369      8369               
===============================================
  Files            573       573               
  Lines          33929     33938        +9     
  Branches        5667      5667               
===============================================
+ Hits           23111     23118        +7     
- Misses          8629      8631        +2     
  Partials        2189      2189

Impacted Files	Coverage Δ	Complexity Δ
.../variant/variantcontext/VariantContextBuilder.java	82.635% <100%> (+0.105%)	39 <0> (ø)	:arrow_down:
src/main/java/htsjdk/variant/vcf/VCFEncoder.java	85.859% <82.927%> (-0.457%)	68 <10> (ø)

[yfarjoun]

Thanks @lbergelson for taking over this. happy with your changes with a few comments. Feel free to merge after addressing them.