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    Use dlsym to check if libdl is needed for plugin · 3cba8b6c
    H.J. Lu authored
    config/plugins.m4 has
    
     if test "$plugins" = "yes"; then
        AC_SEARCH_LIBS([dlopen], [dl])
      fi
    
    Plugin uses dlsym, but libasan.so only intercepts dlopen, not dlsym:
    
    [hjl@gnu-tools-1 binutils-text]$ nm -D /lib64/libasan.so.4| grep " dl"
    0000000000038580 W dlclose
                     U dl_iterate_phdr
    000000000004dc50 W dlopen
                     U dlsym
                     U dlvsym
    [hjl@gnu-tools-1 binutils-text]$
    
    Testing dlopen for libdl leads to false negative when -fsanitize=address
    is used.  It results in link failure:
    
    ../bfd/.libs/libbfd.a(plugin.o): undefined reference to symbol 'dlsym@@GLIBC_2.16'
    
    dlsym should be used to check if libdl is needed for plugin.
    
    bfd/
    
    	PR gas/22318
    	* configure: Regenerated.
    
    binutils/
    
    	PR gas/22318
    	* configure: Regenerated.
    
    gas/
    
    	PR gas/22318
    	* configure: Regenerated.
    
    gprof/
    
    	PR gas/22318
    	* configure: Regenerated.
    
    ld/
    
    	PR gas/22318
    	* configure: Regenerated.
    3cba8b6c