MinGW PostgreSQL builds do not work correctly

I was trying to run a PostgreSQL server under ReactOS. First roadblock, ReactOS' only user available is Administrator, which PostgreSQL prevents being ran as. Okay, I'll edit Postgres to remove the admin check and rebuild. Edited src/backend/main/main.c and compiled with i686-w64-mingw32, not MSVC (which I don't have). Instead of getting to the point of check for Administrator, initdb (or any other program that comes with it), complains about not being able to find its own programs and others it needs for a successful run. This same build works as expected under Windows XP.

Steps to reproduce:
1. Build (or use the build I link below) PostgreSQL with i686-w64-mingw32, removing the admin check in src/backend/main/main.c
2. Place it anywhere in your system. I used C:\pgsql because it's simple
3. (Optional step) add C:\pgsql\bin in your PATH. I did this on both OSes by going to System Properties and making a PATH variable for the user.
4. Try to initialize the database cluster with the command "initdb C:\DB"

Custom pgsql download: https://chungy.keybase.pub/pgsql-10.3.zip