Remove extra parens around equality checks

[mcol]

Summary

Besides the extra parens mentioned in #593, I found a few more. The only other case I spotted but decided not to change was in stan/math/prim/scal/fun/sign.hpp, as I thought it would be slightly more clear as is:

return (z == 0) ? 0 : z < 0 ? -1 : 1;

I also looked around inequality checks, but found none to fix. Fixes #593.

Tests

Nothing new.

Side Effects

None.

Checklist

• Math issue Remove parens around equality checks #593

• Copyright holder: Marco Colombo

  The copyright holder is typically you or your assignee, such as a university or company. By submitting this pull request, the copyright holder is agreeing to the license the submitted work under the following licenses:
  - Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
  - Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

• the basic tests are passing

  • unit tests pass (to run, use: ./runTests.py test/unit)
  • header checks pass, (make test-headers)
  • docs build, (make doxygen)
  • code passes the built in C++ standards checks (make cpplint)

• the code is written in idiomatic C++ and changes are documented in the doxygen

• the new changes are tested

[stan-buildbot]

(stat_comp_benchmarks/benchmarks/gp_pois_regr/gp_pois_regr.stan, 0.99)
(stat_comp_benchmarks/benchmarks/low_dim_corr_gauss/low_dim_corr_gauss.stan, 1.02)
(stat_comp_benchmarks/benchmarks/irt_2pl/irt_2pl.stan, 1.0)
(stat_comp_benchmarks/benchmarks/pkpd/one_comp_mm_elim_abs.stan, 1.0)
(stat_comp_benchmarks/benchmarks/eight_schools/eight_schools.stan, 1.0)
(stat_comp_benchmarks/benchmarks/gp_regr/gp_regr.stan, 0.99)
(stat_comp_benchmarks/benchmarks/arK/arK.stan, 0.99)
(performance.compilation, 1.01)
(stat_comp_benchmarks/benchmarks/low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan, 0.99)
(stat_comp_benchmarks/benchmarks/low_dim_gauss_mix/low_dim_gauss_mix.stan, 1.0)
(stat_comp_benchmarks/benchmarks/sir/sir.stan, 1.03)
(stat_comp_benchmarks/benchmarks/pkpd/sim_one_comp_mm_elim_abs.stan, 1.0)
(stat_comp_benchmarks/benchmarks/garch/garch.stan, 0.99)
(stat_comp_benchmarks/benchmarks/gp_regr/gen_gp_data.stan, 0.98)
(stat_comp_benchmarks/benchmarks/arma/arma.stan, 1.01)
Result: 1.00023717847
Commit hash: 1569474

[stan-buildbot]

(stat_comp_benchmarks/benchmarks/gp_pois_regr/gp_pois_regr.stan, 1.0)
(stat_comp_benchmarks/benchmarks/low_dim_corr_gauss/low_dim_corr_gauss.stan, 0.99)
(stat_comp_benchmarks/benchmarks/irt_2pl/irt_2pl.stan, 1.01)
(stat_comp_benchmarks/benchmarks/pkpd/one_comp_mm_elim_abs.stan, 1.06)
(stat_comp_benchmarks/benchmarks/eight_schools/eight_schools.stan, 1.01)
(stat_comp_benchmarks/benchmarks/gp_regr/gp_regr.stan, 1.0)
(stat_comp_benchmarks/benchmarks/arK/arK.stan, 1.0)
(performance.compilation, 1.01)
(stat_comp_benchmarks/benchmarks/low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan, 1.01)
(stat_comp_benchmarks/benchmarks/low_dim_gauss_mix/low_dim_gauss_mix.stan, 1.0)
(stat_comp_benchmarks/benchmarks/sir/sir.stan, 0.97)
(stat_comp_benchmarks/benchmarks/pkpd/sim_one_comp_mm_elim_abs.stan, 0.94)
(stat_comp_benchmarks/benchmarks/garch/garch.stan, 0.99)
(stat_comp_benchmarks/benchmarks/gp_regr/gen_gp_data.stan, 1.0)
(stat_comp_benchmarks/benchmarks/arma/arma.stan, 0.98)
Result: 0.99756798938
Commit hash: 1569474