[Q] How can I add missing symbols to a proprietary .so? - Android Q&A, Help & Troubleshooting

Is it possible to add some missing symbols to existing shared libraries?
The stock libaudio.so on Milestone XT720 references three static strings found in the stock libmedia.so that are not common in other ROMs. Basically, the relevant parts in the original proprietaries are (via nm -D)
Code:
libaudio.so:
U _ZN7android14AudioParameter11keyFMLaunchE
U _ZN7android14AudioParameter12keyFMRoutingE
U _ZN7android14AudioParameter14keyHDMIRoutingE
Code:
libmedia.so:
0005fb68 D _ZN7android14AudioParameter11keyFMLaunchE
0005fb6c D _ZN7android14AudioParameter12keyFMRoutingE
0005fb70 D _ZN7android14AudioParameter14keyHDMIRoutingE
Code wise, we've figured out that they're just these stupid static strings
Code:
namespace android {
class AudioParameter {
static const char *keyFMLaunch;
static const char *keyFMRouting;
static const char *keyHDMIRouting;
};
const char *AudioParameter::keyFMLaunch = "FM_launch";
const char *AudioParameter::keyFMRouting = "FM_routing";
const char *AudioParameter::keyHDMIRouting ="HDMI_routing";
}; // namespace android
For example we're mostly compatible with Milestone A853's stock ROM, but Milestone A853's libmedia.so doesn't have these symbols, so we get link failure and substituting our libmedia.so causes big problems. If we use Milestone A853's libaudio.so instead, then FM radio volume control doesn't work.
AOSP/CyanogenMod don't have these symbols in libmedia either, so we've been using a forked framework/base just to stick these symbols in. I'm trying to clean up our tree and if it's possible I'd rather just stuff those symbols into libaudio.so somehow and never think about it again.
Is there some way to copy those strings from libmedia.so? I've been trying some things with the various binutils (objcopy, ld) and scouring man pages but no luck so far. I put the code above in wrapper.cpp but I can't figure out whether gcc can add to an existing .so. Any suggestions? I'm happy to read if someone knows where to point me.