Solved, it seems.
Not really, as it doesn't explain where my original issue came from. :P
What had happened was I'd been working on my little Xmas game program, and while taking a break I figured, "Hey, I haven't updated my repo for a while!", while making the little blinking QB64-Xmas IDE... I popped onto Github, closed all my QB64 windows, and did the "pull from source" to update my version of QB64. It mentioned "You have 1234567890 changes in your local repo, do you want to stash them first?", so I clicked "SURE" and stashed them to do the update.
After the update I clicked "Discard stashed changes", and here's where a few odd things started to pop up...
Github, as expected, cleared all my old resource files and such, requiring me to reinstall them back over to my QB64 directory. No problem, as I always keep those things zipped up in their own folders in a dozen other places, at all times. Oddly enough, Github didn't "stash and delete" any of my BAS files, even though it cleared everything else out of the directories they were in. Go figure! LOL!
falcon.h was removed from the Xmas folder, so I recopied another version of it into the proper place and then did a quick "setup_win.bat" to rebuild the latest QB64. Once I had the newest QB64, I loaded up my program that had ran perfectly 5 minutes before, compiled it, and I got the original error log I'd posted in the first post.
C:\Users\the_r\AppData\Local\Temp\ccjqRJ4V.o:qbx.cpp:(.text+0x838): undefined reference to `FT_Get_Char_Index'
C:\Users\the_r\AppData\Local\Temp\ccjqRJ4V.o:qbx.cpp:(.text+0x86c): undefined reference to `FT_Get_Kerning'
C:\Users\the_r\AppData\Local\Temp\ccjqRJ4V.o:qbx.cpp:(.text+0x88e): undefined reference to `FT_Load_Glyph'
C:\Users\the_r\AppData\Local\Temp\ccjqRJ4V.o:qbx.cpp:(.text+0x8b0): undefined reference to `FT_Render_Glyph'
C:\Users\the_r\AppData\Local\Temp\ccjqRJ4V.o:qbx.cpp:(.rdata$.refptr.fonts[.refptr.fonts]+0x0): undefined reference to `fonts'
Stripping out falcon.h from the program, and compiling it without _LOADFONT or _FONT explains the issue with the stripped down version, but it doesn't explain why it was failing in the original program where it worked before the repo updated.
The best I can figure is that the g++ compiler is the one that was making the temp windows files (I don't think we have anywhere in QB64 that uses "USER\Temp\" as a path, do we??), and something was going wrong with those files.
Playing around for a while didn't get me anywhere, so I cleaned Windows of all its Temp junk, deleting all the existing temp files it had stored in those folders, and then PRESTO-- things worked once I added the .c file and removed "extern" from the fonts declaration in falcon.h. After the test code compiled itself, I then loaded back my original Xmas game code, and gave it a go.... only to have it toss a zillion duplicate definition errors. /SIGH
Why updating the repo caused it to fail the first time is completely beyond me, unless it just had something to do with the old QB64 version having created a USER/Temp/ccjqRJ4V.o file previously, that didn't quite match up to what the latest version expected... Since the file existed, it wasn't recreating it, and since it was an outdated version, something went wacky... is my guess??
Honestly, I don't know how updating the repo broke QB64 for me, but it did. :P
Somewhere between the github "Stash" and "delete" and update and install, something went wrong somewhere. Heck, I'd never even thought about g++ using the windows Temp folders before with QB64, but apparently they do somewhere along the process to compilation, as indicated by the error messages above. Whatever the glitch was this time around, it appears to be on the g++ compiler side of things, rather than on the QB64 side of the fence.
Whatever it was, I'm just glad that *something* finally cleared it up and made it go away for me! LOL! ;D