v26.01 release

This release introduces AdvSIMD/SVE log, rsqrt, and pow variants;
expands fp/ with complete double-precision arithmetic and conversions;
and broadens CI/platform coverage while tightening pow/log/exp
special-case handling, simplifying math configuration, and improving
tests and benchmarks.

**Main AOR directory**

Add
 * Add cygwin/newlib support for the string routines and tests.
 * Update GitHub runners to refresh apt packages before installing dependencies.

Change
 * aarch64 assembly now emits .cfi_negate_ra_state for correct unwind info.
 * bench: Fix the memset benchmark typo that overflowed the size array.

**fp/**

Add
 * Implement double-precision addition/subtraction, division, and comparisons.
 * Add conversions between integers and double precision as well as between single and double precision.
 * Replace the stub ui2f test with a real one and add GNU-style comparison helpers.

Change
 * Rename the aux subdirectory and register aliases to avoid Windows toolchain issues.
 * Apply multiple GNU assembler build fixes across the new fp sources.

**math/**

Add
 * aarch64: Implement AdvSIMD log2p1 and SVE log2p1(f).
 * aarch64: Implement AdvSIMD and SVE log10p1(f).
 * aarch64: Implement AdvSIMD and SVE rsqrt(f).
 * aarch64: Implement AdvSIMD and SVE powr(f) plus shared helpers.
 * aarch64: Implement AdvSIMD special case helper for exponentials.
 * aarch64: Provide return-by-value AdvSIMD and SVE modf(f) and sincospi(f).

Change
 * Remove float_t/double_t usage and drop WANT_SIMD_EXCEPT to simplify configuration.
 * aarch64: Rework pow(f) and powr helpers, vectorise special cases, and fix negative or special argument handling.
 * aarch64/advsimd: Optimise log/log1p/log2/log10 (float and double).
 * aarch64/advsimd: Optimise atanhf, asinhf, acoshf, tan, and sinh.
 * aarch64/advsimd: Optimise vectorised special cases for expf, exp2f, exp10f, exp2m1f, exp10m1f via new helpers.
 * aarch64/advsimd: Vectorise expm1/expm1f special cases.
 * aarch64/experimental: Remove ldexp from expm1(f).
 * aarch64/sve: Improve scalar callbacks and special-case buffers.
 * aarch64/sve: Vectorise exp/exp2/exp10/expm1 fallbacks.

**Full Changelog**: v25.07...26.01

Author: DylanFleming-arm

README.md

@@ -120,7 +120,7 @@ Regular biannual releases are tagged as `vYY.MM`. All release are available at
 [https://github.com/ARM-software/optimized-routines/releases]().
 
 The latest release is
-[https://github.com/ARM-software/optimized-routines/releases/tag/v25.07](v25.07).
+[https://github.com/ARM-software/optimized-routines/releases/tag/v26.01](v26.01).
 
 ---