Some tweaks to the SVE2p1 load and store intrinsics (#359)

The pre-SVE2p1 gather and scatter intrinsics allow vector displacements
(offsets or indices) to be either signed or unsigned. svld1q and svst1q
instead required them to be unsigned. This patch adds signed versions
too, for consistency.

Also, the SVE2p1 stores were specified to take pointers to const, but
they ought to be pointers to non-const instead.

main/acle.md

@@ -431,6 +431,7 @@ Armv8.4-A [[ARMARMv84]](#ARMARMv84). Support is added for the Dot Product intrin
 * Changed `__ARM_NEON_SVE_BRIDGE` to refer to the availability of the
   [`arm_neon_sve_bridge.h`](#arm_neon_sve_bridge.h) header file, rather
   than the [NEON-SVE bridge](#neon-sve-bridge) intrinsics.
+* Removed extraneous `const` from SVE2.1 store intrinsics.
 
 ### References
 
@@ -9221,11 +9222,13 @@ Gather Load Quadword.
    // _mf8, _bf16, _f16, _f32, _f64
    svint8_t svld1q_gather[_u64base]_s8(svbool_t pg, svuint64_t zn);
    svint8_t svld1q_gather[_u64base]_offset_s8(svbool_t pg, svuint64_t zn, int64_t offset);
+   svint8_t svld1q_gather_[s64]offset[_s8](svbool_t pg, const int8_t *base, svint64_t offset);
    svint8_t svld1q_gather_[u64]offset[_s8](svbool_t pg, const int8_t *base, svuint64_t offset);
 
    // Variants are also available for:
    // _u16, _u32, _s32, _u64, _s64
    // _bf16, _f16, _f32, _f64
+   svint16_t svld1q_gather_[s64]index[_s16](svbool_t pg, const int16_t *base, svint64_t index);
    svint16_t svld1q_gather_[u64]index[_s16](svbool_t pg, const int16_t *base, svuint64_t index);
    svint16_t svld1q_gather[_u64base]_index_s16(svbool_t pg, svuint64_t zn, int64_t index);
    ```
@@ -9295,14 +9298,14 @@ Contiguous store of single vector operand, truncating from quadword.
 ``` c
    // Variants are also available for:
    // _u32, _s32
-   void svst1wq[_f32](svbool_t, const float32_t *ptr, svfloat32_t data);
-   void svst1wq_vnum[_f32](svbool_t, const float32_t *ptr, int64_t vnum, svfloat32_t data);
+   void svst1wq[_f32](svbool_t, float32_t *ptr, svfloat32_t data);
+   void svst1wq_vnum[_f32](svbool_t, float32_t *ptr, int64_t vnum, svfloat32_t data);
 
 
    // Variants are also available for:
    // _u64, _s64
-   void svst1dq[_f64](svbool_t, const float64_t *ptr, svfloat64_t data);
-   void svst1dq_vnum[_f64](svbool_t, const float64_t *ptr, int64_t vnum, svfloat64_t data);
+   void svst1dq[_f64](svbool_t, float64_t *ptr, svfloat64_t data);
+   void svst1dq_vnum[_f64](svbool_t, float64_t *ptr, int64_t vnum, svfloat64_t data);
    ```
 
 #### ST1Q
@@ -9315,12 +9318,14 @@ Scatter store quadwords.
    // _mf8, _bf16, _f16, _f32, _f64
    void svst1q_scatter[_u64base][_s8](svbool_t pg, svuint64_t zn, svint8_t data);
    void svst1q_scatter[_u64base]_offset[_s8](svbool_t pg, svuint64_t zn, int64_t offset, svint8_t data);
-   void svst1q_scatter_[u64]offset[_s8](svbool_t pg, const uint8_t *base, svuint64_t offset, svint8_t data);
+   void svst1q_scatter_[s64]offset[_s8](svbool_t pg, uint8_t *base, svint64_t offset, svint8_t data);
+   void svst1q_scatter_[u64]offset[_s8](svbool_t pg, uint8_t *base, svuint64_t offset, svint8_t data);
 
    // Variants are also available for:
    // _u16, _u32, _s32, _u64, _s64
    // _bf16, _f16, _f32, _f64
-   void svst1q_scatter_[u64]index[_s16](svbool_t pg, const int16_t *base, svuint64_t index, svint16_t data);
+   void svst1q_scatter_[s64]index[_s16](svbool_t pg, int16_t *base, svint64_t index, svint16_t data);
+   void svst1q_scatter_[u64]index[_s16](svbool_t pg, int16_t *base, svuint64_t index, svint16_t data);
    void svst1q_scatter[_u64base]_index[_s16](svbool_t pg, svuint64_t zn, int64_t index, svint16_t data);
 ```