[PATCH] AArch64: Improve enabling of SVE for libmvec

[Wilco Dijkstra]

When using a -mcpu option in CFLAGS, GCC can report errors when building libmvec.
Fix this by overriding both -mcpu and -march with a generic variant with SVE added.
Also use a tune for a modern SVE core.

OK for commit?

---

diff --git a/sysdeps/aarch64/fpu/Makefile b/sysdeps/aarch64/fpu/Makefile
index 7b0ec3e9a94a7f83689c641bd5771ea2575a760b..9efbe1f78dad38bcea8f3fbf10f5b7079212d9a5 100644
--- a/sysdeps/aarch64/fpu/Makefile
+++ b/sysdeps/aarch64/fpu/Makefile
@@ -56,8 +56,11 @@ libmvec-support = $(addsuffix f_advsimd,$(float-advsimd-funcs)) \
                   v_powf_data
 endif
 
-sve-cflags = -march=armv8-a+sve
+# Enable SVE for building libmvec.  Since CFLAGS may contain a -mcpu or -march,
+# add a generic -mcpu and -march with SVE enabled.  Also use a tune for a modern
+# SVE core.
 
+sve-cflags = -mcpu=generic+sve -march=armv8-a+sve -mtune=neoverse-v2
 
 ifeq ($(build-mathvec),yes)
 bench-libmvec = $(addprefix float-advsimd-,$(float-advsimd-funcs)) \