Add missing AT tags to the ELF common header. * elf/common.h (AT_L1I_CACHESIZE, AT_L1I_CACHEGEOMETRY) (AT_L1D_CACHESIZE, AT_L1D_CACHEGEOMETRY, AT_L2_CACHESIZE) (AT_L2_CACHEGEOMETRY, AT_L3_CACHESIZE, AT_L3_CACHEGEOMETRY) (AT_MINSIGSTKSZ): New defines, imported from glibc.