goalc: Fix new symbol trie's performance inefficiencies

[xTVaser]

I believe this brings things back in line to where it was before:
Here are the first handful of files before the changes:

0.014 | gcommon.gc
0.006 | gkernel-h.gc
0.025 | gkernel.gc
0.002 | pskernel.gc
0.01 | gstring.gc
0.004 | gstate.gc
0.001 | kernel.gd
0.001 | types-h.gc
0.002 | vu1-macros.gc
0.003 | math.gc
0.01 | vector-h.gc
0.001 | gravity-h.gc
0.001 | bounding-box-h.gc
0.001 | matrix-h.gc
0.001 | quaternion-h.gc
0.001 | euler-h.gc

first compile

0.161 | gcommon.gc
0.126 | gkernel-h.gc
0.174 | gkernel.gc
0.046 | pskernel.gc
0.08 | gstring.gc
0.048 | gstate.gc
0.001 | kernel.gd
0.052 | types-h.gc
0.009 | vu1-macros.gc
0.059 | math.gc
0.228 | vector-h.gc
0.026 | gravity-h.gc
0.006 | bounding-box-h.gc
0.002 | matrix-h.gc
0.028 | quaternion-h.gc
0.026 | euler-h.gc

make a change in gcommon and recompile

With the changes:

0.015 | gcommon.gc
0.018 | gkernel-h.gc
0.039 | gkernel.gc
0.006 | pskernel.gc
0.015 | gstring.gc
0.009 | gstate.gc
0.005 | kernel.gd
0.006 | types-h.gc
0.006 | vu1-macros.gc
0.008 | math.gc
0.017 | vector-h.gc
0.004 | gravity-h.gc
0.004 | bounding-box-h.gc
0.005 | matrix-h.gc
0.005 | quaternion-h.gc
0.003 | euler-h.gc

First compile, no difference expected

0.016 | gcommon.gc
0.008 | gkernel-h.gc
0.023 | gkernel.gc
0.002 | pskernel.gc
0.01 | gstring.gc
0.043 | gstate.gc
0.001 | kernel.gd
0.002 | types-h.gc
0.002 | vu1-macros.gc
0.003 | math.gc
0.013 | vector-h.gc
0.001 | gravity-h.gc
0.002 | bounding-box-h.gc
0.002 | matrix-h.gc
0.001 | quaternion-h.gc
0.001 | euler-h.gc

Compile times seem to be back within margin of error -- some are faster than the first compilation time.

[water111]

Nice! This trie has a much better implementation.