I tried building Gimp and noticed the build was picking up base-gcc for some portions of the build. I fixed something similar with QEMU. It has a separate macro that seems to deal with a native compiler vs cross compiler which QEMU was doing as well.
Index: Makefile =================================================================== RCS file: /home/cvs/ports/graphics/gimp/stable/Makefile,v retrieving revision 1.140 diff -u -p -u -p -r1.140 Makefile --- Makefile 6 Dec 2020 08:33:18 -0000 1.140 +++ Makefile 19 Dec 2020 04:42:40 -0000 @@ -3,7 +3,7 @@ COMMENT= GNU Image Manipulation Program DISTNAME = gimp-2.10.22 -REVISION = 0 +REVISION = 1 .for i in gimp gimpbase gimpcolor gimpconfig gimpmath gimpmodule \ gimpthumb gimpui gimpwidgets @@ -90,7 +90,8 @@ LIB_DEPENDS= archivers/bzip2 \ x11/gnome/librsvg \ x11/gtk+2>=2.24.10 -CONFIGURE_ENV= CPPFLAGS="-I${LOCALBASE}/include -I${X11BASE}/include" \ +CONFIGURE_ENV= CC_FOR_BUILD="${CC}" \ + CPPFLAGS="-I${LOCALBASE}/include -I${X11BASE}/include" \ LDFLAGS="-L${LOCALBASE}/lib -L${X11BASE}/lib" USE_GMAKE= Yes