[libc][math] Simplify tanf implementation and improve its performance.
Simplify `tanf` implementation and improve its performance.
Completely reuse the implementation of `sinf`, `cosf`, `sincosf` and use
the definition `tan(x) = sin(x)/cos(x)`.
Performance benchmark using perf tool from the CORE-MATH project on Ryzen 1700:
```
$ CORE_MATH_PERF_MODE="rdtsc" ./perf.sh tanf
GNU libc version: 2.35
GNU libc release: stable
CORE-MATH reciprocal throughput : 18.558
System LIBC reciprocal throughput : 49.919
BEFORE:
LIBC reciprocal throughput : 36.480
LIBC reciprocal throughput : 27.217 (with `-msse4.2` flag)
LIBC reciprocal throughput : 20.205 (with `-mfma` flag)
AFTER:
LIBC reciprocal throughput : 30.337
LIBC reciprocal throughput : 21.072 (with `-msse4.2` flag)
LIBC reciprocal throughput : 15.804 (with `-mfma` flag)
$ CORE_MATH_PERF_MODE="rdtsc" ./perf.sh tanf --latency
GNU libc version: 2.35
GNU libc release: stable
CORE-MATH latency : 56.702
System LIBC latency : 107.206
BEFORE
LIBC latency : 97.598
LIBC latency : 91.119 (with `-msse4.2` flag)
LIBC latency : 82.655 (with `-mfma` flag)
AFTER
LIBC latency : 74.560
LIBC latency : 66.575 (with `-msse4.2` flag)
LIBC latency : 61.636 (with `-mfma` flag)
```
Reviewed By: zimmermann6
Differential Revision: https://reviews.llvm.org/D134575