mesa: remove useless OpenCL libraries #85

Job	Run time
Feeds Package Test Build / Test aarch64_generic	3h 19m 27s
Feeds Package Test Build / Test arm_cortex-a15_neon-vfpv4	4h 6m 3s
Feeds Package Test Build / Test arm_cortex-a9_vfpv3-d16	3h 58m 9s
Feeds Package Test Build / Test i386_pentium-mmx	3h 18m 34s
Feeds Package Test Build / Test mips_24kc	3h 51m 29s
Feeds Package Test Build / Test mipsel_24kc	3h 50m 44s
Feeds Package Test Build / Test powerpc_464fp	24m 25s
Feeds Package Test Build / Test powerpc_8548	24m 38s
Feeds Package Test Build / Test riscv64_riscv64	3h 23m 38s
Feeds Package Test Build / Test x86_64	3h 19m 58s
	1d 5h 57m 5s

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