Revert "we no longer need fixprefix", because we do need it. On cross compiling. On mingw it is harmless.

This reverts commit 189385d856.

mingw-Makefile.inc

@@ -4,6 +4,9 @@ MINGW_EXEC_PREFIX ?=
 # where the dependencies package is extracted
 RADIANT_DEPENDENCIES_PREFIX = $(HOME)/radiant-deps-mingw32/
 
+# run the prefix fixing tool
+IGNORETHIS := $(shell cd $(RADIANT_DEPENDENCIES_PREFIX) && ./fixprefix.sh)
+
 # set the environment for make
 OS = Win32
 CFLAGS +=