ARM: remove -mshort-load-bytes / -malignment-traps
add __aeabi_memcpy __aeabi_memset

fixes this:

common/libcommon.o: In function `env_callback_init':
/home/jeroen/software/u-boot/common/env_callback.c:47: undefined reference to `__aeabi_memset'
common/libcommon.o: In function `parse_stream_outer':
/home/jeroen/software/u-boot/common/hush.c:3154: undefined reference to `__aeabi_memset'
disk/libdisk.o: In function `get_device_and_partition':
/home/jeroen/software/u-boot/disk/part.c:596: undefined reference to `__aeabi_memcpy'
/home/jeroen/software/u-boot/disk/part.c:605: undefined reference to `__aeabi_memcpy'
fs/fat/libfat.o: In function `fat_set_blk_dev':
/home/jeroen/software/u-boot/fs/fat/fat.c:60: undefined reference to `__aeabi_memcpy'
fs/ubifs/libubifs.o: In function `ubifs_tnc_locate':
/home/jeroen/software/u-boot/fs/ubifs/tnc.c:1457: undefined reference to `__aeabi_memcpy'
fs/ubifs/libubifs.o: In function `tnc_insert':
/home/jeroen/software/u-boot/fs/ubifs/tnc.c:2008: undefined reference to `__aeabi_memcpy'
fs/ubifs/libubifs.o:/home/jeroen/software/u-boot/fs/ubifs/tnc.c:2333: more undefined references to `__aeabi_memcpy' follow
arm-linux-gnueabi-ld.bfd: BFD (GNU Binutils for Ubuntu) 2.23.2 assertion fail ../../bfd/elf32-arm.c:7683
arm-linux-gnueabi-ld.bfd: BFD (GNU Binutils for Ubuntu) 2.23.2 assertion fail ../../bfd/elf32-arm.c:7683
arm-linux-gnueabi-ld.bfd: error: required section '.rel.plt' not found in the linker script
arm-linux-gnueabi-ld.bfd: final link failed: Invalid operation
clang script