[SVE] Add support for the SVE target.

[fpetrogalli]

This commit adds support for the AArch64 Scalable Vector Extension
(SVE) [1]. The vector functions are provided to target Vector Length
Agnostic (VLA) execution [2].

To build SLEEF with SVE support, a compiler that support the SVE Arm C
Language Extensions (ACLE) [2] must be used.

At the time of publishing this patch, the only compiler with SVE ACLE
support is Arm Compiler for HPC [3].

The Cmake configuration expectes Arm Instruction Emulator (ArmIE) [4]
to execute the tests on native AArch64 hardware without SVE support.

The SVE target is build without taking advantage of the native masking
capabilities of SVE. This will be targeted in a upcoming release of
SLEEF, together with the AVX512F native masking capabilities [5].

Additional changes introduced in this patch are:

1. The mkrename* script have been modified to support VLA names in the
   functions. In particular, 'x' is used to represent the vector
   length of the SVE symbols.

2. '__sizeless_struct' is a prototype language extension only
   implemented by Arm Compiler For HPC [3] to allow the declaration of
   SVE tuple types as described in section 3.4 of Arm C Language
   Extensions for SVE [2].

3. A new 'iutsve' executable is generated to test the SVE functions.

[1] https://developer.arm.com/products/software-development-tools/hpc/sve
[2] https://developer.arm.com/docs/100987/0000
[3] https://developer.arm.com/products/software-development-tools/hpc/arm-compiler-for-hpc
[4] https://developer.arm.com/products/software-development-tools/hpc/arm-instruction-emulator
[5] #142

[shibatch]

Looks good to me.
I confirmed that the test passes with SVE on my environment.
We need to think of a way to enable testing on a CI environment, though.

[fpetrogalli]

Did you use armclang and armie?

[shibatch]

yes

[fpetrogalli]

Might be a good idea to report the ctest output here (just the run test/test passed).

[shibatch]

Here you are.

[uduki]~/work/sleef3/sleef-enable-sve/build-aarch64$ ctest -j 4
Test project /import/namihei.naist.jp/home/n-sibata/work/sleef3/sleef-enable-sve/build-aarch64
      Start  1: iut
      Start  2: iutadvsimd
      Start  3: iutsve
      Start  4: gnuabi_compatibility_ADVSIMD
 1/18 Test  #4: gnuabi_compatibility_ADVSIMD ......   Passed    0.04 sec
      Start  5: gnuabi_compatibility_SVE
 2/18 Test  #5: gnuabi_compatibility_SVE ..........   Passed    0.01 sec
      Start  6: gnuabi_compatibility_SVE_masked
 3/18 Test  #6: gnuabi_compatibility_SVE_masked ...   Passed    0.01 sec
      Start  7: naivetestdp_1
 4/18 Test  #7: naivetestdp_1 .....................   Passed    0.04 sec
      Start  8: naivetestdp_2
 5/18 Test  #8: naivetestdp_2 .....................   Passed    0.02 sec
      Start  9: naivetestdp_3
 6/18 Test  #9: naivetestdp_3 .....................   Passed    0.03 sec
      Start 10: naivetestdp_4
 7/18 Test #10: naivetestdp_4 .....................   Passed    0.03 sec
      Start 11: naivetestdp_5
 8/18 Test #11: naivetestdp_5 .....................   Passed    0.04 sec
      Start 12: naivetestdp_10
 9/18 Test #12: naivetestdp_10 ....................   Passed    2.81 sec
      Start 13: naivetestsp_1
10/18 Test #13: naivetestsp_1 .....................   Passed    0.02 sec
      Start 14: naivetestsp_2
11/18 Test #14: naivetestsp_2 .....................   Passed    0.41 sec
      Start 15: naivetestsp_3
12/18 Test #15: naivetestsp_3 .....................   Passed    0.03 sec
      Start 16: naivetestsp_4
13/18 Test #16: naivetestsp_4 .....................   Passed    0.02 sec
      Start 17: naivetestsp_5
14/18 Test #17: naivetestsp_5 .....................   Passed    0.04 sec
      Start 18: naivetestsp_10
15/18 Test #18: naivetestsp_10 ....................   Passed    2.85 sec
16/18 Test  #1: iut ...............................   Passed  334.39 sec
17/18 Test  #2: iutadvsimd ........................   Passed  352.21 sec
18/18 Test  #3: iutsve ............................   Passed  672.23 sec

100% tests passed, 0 tests failed out of 18

Total Test time (real) = 672.43 sec
[uduki]~/work/sleef3/sleef-enable-sve/build-aarch64$

[fpetrogalli]

Thanks. What system are you using?

[shibatch]

This one is Firefly-RK3399.