install: put a symlink as well in the 4.5 profile prefix

Without this symlink in place from the 4.5 profile folder to
4.0's fsc.exe, xbuild gives an error because it is somehow
looking for it in the 4.5 profile (that should be investigated
but for now this workaround does the trick smartly enough).

src/fsharp/Fsc/Makefile.in

@@ -33,5 +33,5 @@ $(tmpdir)FSCstrings.resources: $(srcdir)../FSCstrings.txt
 
 include $(topdir)/src/fsharp/targets.make
 
-install: install-bin-2 install-bin-4
+install: install-bin-2 install-bin-4 install-bin-4-5
 

src/fsharp/targets.make

@@ -115,6 +115,11 @@ install-bin-2 install-bin-4:
 	$(INSTALL_LIB) $(outdir)$(ASSEMBLY) $(DESTDIR)$(libdir)mono/$(TARGET)
 	$(INSTALL_BIN) $(outdir)$(subst fs,fsharp,$(NAME))$(VERSION) $(DESTDIR)/$(bindir)
 
+install-bin-4-5: install-bin-4
+	@if test -e $(DESTDIR)$(libdir)mono/4.5/; then \
+		ln -fs $(DESTDIR)$(libdir)mono/4.0/$(ASSEMBLY) $(DESTDIR)$(libdir)mono/4.5/$(ASSEMBLY); \
+	fi
+
 $(objdir) $(objdir)$(TARGET_2_0) $(objdir)$(TARGET_4_0):
 	mkdir -p $@