build: avoid usage of PHONY (GNU make only)

Was not working with the NDK tool chain

Issue: #78221
Change-Id: I7b8fd4eaebce410b41efe955b0fa800cf8319d4c
Signed-off-by: Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>

src/Makefile.am

@@ -170,4 +170,8 @@ nobase_include_HEADERS+= \
 		dring/videomanager_interface.h
 endif
 
-.PHONY: buildinfo.cpp
+# Force buildinfo to be remade at each build
+buildinfo.cpp: FORCE
+	@touch buildinfo.cpp
+
+FORCE:;