did you update your devkit_ARM recently ?
did you ever managed to compile that project?
if you are trying to compile an older project, you might have to use older devkitARM revision.
newer version of GCC/devkitARM/DevkitPPC require more strict way fo coding.
instead of updating devkitpro, you should downgrade it, or you might have to fix the sources to compile with latest devkit revision.
if you want to use an older version :
1. get devkitPPC or devkitARM version you want here
https://sourceforge.net/projects/devkitpro/files/devkitARM/
2. extract it to devkitpro folder but rename it, to keep multiple version.
DO NOT INSTALL, extract it (right click -> 7zip -> open, etc.)
example :
devkitPro/devkitARM/ <-- keep this folder with default, latest revision, r47
devkitPro/devkitARM_r45/ <-- folder with revision 45
devkitPro/devkitARM_r44/ <-- folder with revision 44
3. before compiling, change the environment variable path temporarily to the revision you want to use
It affects only the current command line window, and will not conflict with other projects. you have to type it every time you open a new command line window, it's temporary only.
set DEVKITARM=/c/devkitPro/devkitARM_r45/
make
note that you might have to use older libraries too, the one used when that project was maintained.