Improve [SD]SYEVD performance by parallelizing [SD]LAED3 #2205

Job	Run time
TEST (LOONGSON2K1000, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LOONGSON2K1000)	13m 38s
TEST (LOONGSONGENERIC, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LOONGSONGENERIC)	14m 43s
TEST (DYNAMIC_ARCH, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=GENERIC)	16m 18s
TEST (LA264, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LA264)	13m 49s
TEST (LA64_GENERIC, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LA64_GENERIC)	48m 47s
TEST (LOONGSON3R5, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LOONGSON3R5)	42m 4s
TEST (LA464, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LA464)	45m 36s
TEST (LA64_GENERIC, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LA64_GENERIC)	14m 12s
TEST (LA464, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LA464)	45m 36s
TEST (LOONGSONGENERIC, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LOONGSONGENERIC)	14m 43s
TEST (LOONGSON2K1000, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LOONGSON2K1000)	13m 38s
TEST (DYNAMIC_ARCH, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=GENERIC)	16m 18s
TEST (LA264, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LA264)	13m 49s
TEST (LOONGSON3R5, loongarch64-linux-gnu, NO_SHARED=1 DYNAMIC_ARCH=1 TARGET=LOONGSON3R5)	42m 4s
	5h 55m 15s

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