Cleanup unused local typedefs

[andrjohns]

Summary

This PR removes any type definitions that aren't used, as they cause compiler warnings. It also adds the flag -Wunused-local-typedefs to the header tests, to avoid it occurring with new code.

Tests

Adds -Wunused-local-typedefs to header tests

Side Effects

Cleaner codebase

Release notes

Cleanup unused local typedefs

Checklist

• Math issue Cleanup unused typedefs #2504

• Copyright holder: Andrew Johnson

  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)
  • dependencies checks pass, (make test-math-dependencies)
  • 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]

---

Name	Old Result	New Result	Ratio	Performance change( 1 - new / old )
gp_pois_regr/gp_pois_regr.stan	1.97	1.96	1.01	0.69% faster
low_dim_corr_gauss/low_dim_corr_gauss.stan	0.01	0.01	0.98	-1.61% slower
eight_schools/eight_schools.stan	0.06	0.07	0.95	-4.85% slower
gp_regr/gp_regr.stan	0.11	0.1	1.03	2.87% faster
irt_2pl/irt_2pl.stan	3.1	3.17	0.98	-2.21% slower
performance.compilation	64.53	60.72	1.06	5.91% faster
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan	6.18	6.12	1.01	1.04% faster
pkpd/one_comp_mm_elim_abs.stan	18.09	18.28	0.99	-1.03% slower
sir/sir.stan	79.17	79.03	1.0	0.18% faster
gp_regr/gen_gp_data.stan	0.02	0.02	0.97	-3.34% slower
garch/garch.stan	0.33	0.31	1.07	6.82% faster
pkpd/sim_one_comp_mm_elim_abs.stan	0.25	0.25	1.0	-0.29% slower
arK/arK.stan	1.23	1.23	1.0	-0.4% slower
arma/arma.stan	0.43	0.43	1.01	0.91% faster
low_dim_gauss_mix/low_dim_gauss_mix.stan	2.01	2.0	1.0	0.41% faster
Mean result: 1.00433228434

---

Jenkins Console Log
Blue Ocean
Commit hash: ea2134d

---

Machine information

ProductName: Mac OS X ProductVersion: 10.14.6 BuildVersion: 18G8022

CPU:
Intel(R) Core(TM) i7-8700B CPU @ 3.20GHz

G++:
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/usr/include/c++/4.2.1
Apple clang version 11.0.0 (clang-1100.0.33.17)
Target: x86_64-apple-darwin18.7.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

Clang:
Apple clang version 11.0.0 (clang-1100.0.33.17)
Target: x86_64-apple-darwin18.7.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

[rok-cesnovar]

Thanks @andrjohns!