Move 64-bit BFD files from ALL_TARGET_OBS to ALL_64_TARGET_OBS

Move 64-bit BFD files from ALL_TARGET_OBS to ALL_64_TARGET_OBS

Doing a 32-bit build with "--enable-targets=all --disable-sim" fails to link
properly.

--

loongarch-tdep.o: In function `loongarch_gdbarch_init':
binutils-gdb/gdb/loongarch-tdep.c:443: undefined reference to `loongarch_r_normal_name'
loongarch-tdep.o: In function `loongarch_fetch_instruction':
binutils-gdb/gdb/loongarch-tdep.c:37: undefined reference to `loongarch_insn_length'
loongarch-tdep.o: In function `loongarch_scan_prologue(gdbarch*, unsigned long long, unsigned long long, frame_info*, trad_frame_cache*) [clone .isra.4]':
binutils-gdb/gdb/loongarch-tdep.c:87: undefined reference to `loongarch_insn_length'
binutils-gdb/gdb/loongarch-tdep.c:88: undefined reference to `loongarch_decode_imm'
binutils-gdb/gdb/loongarch-tdep.c:89: undefined reference to `loongarch_decode_imm'
binutils-gdb/gdb/loongarch-tdep.c:90: undefined reference to `loongarch_decode_imm'
binutils-gdb/gdb/loongarch-tdep.c:91: undefined reference to `loongarch_decode_imm'
binutils-gdb/gdb/loongarch-tdep.c:92: undefined reference to `loongarch_decode_imm'

--

Given the list of 64-bit BFD files in
opcodes/Makefile.am:TARGET64_LIBOPCODES_CFILES, it looks like GDB's
ALL_TARGET_OBS list is including files that should be included in
ALL_64_TARGET_OBS instead.

This patch accomplishes this and enables a 32-bit build with
"--enable-targets=all --disable-sim" to complete.

Moving the bpf, tilegx and loongarch files to the correct list means GDB can
find the correct disassembler function instead of finding a null pointer.

We still need the "--disable-sim" switch (or "--enable-64-bit-bfd") to
make a 32-bit build with "--enable-targets=all" complete correctly