solaris2.em: Fold after_allocation into before_allocation
    
    Since all ELF linkers call check_relocs after opening all inputs, we
    can fold after_allocation into before_allocation so that local dynamic
    symbols will be placed before global dynamic symbols in .dynsym section.
    This fixed:
    
    FAIL: Common symbol override test (auxiliary shared object build)
    FAIL: ld-elf/pr19617a
    FAIL: ld-elf/pr19698
    
    for i386-solaris2.12 and x86_64-solaris2.12 targets.
    
    	PR ld/22728
    	* emultempl/solaris2.em (elf_solaris2_after_allocation): Fold
    	into ...
    	(elf_solaris2_before_allocation): This.
    	(LDEMUL_AFTER_ALLOCATION): Removed.