gen_makefile: add *.tpl to dependency file list

libosmocore has some *.tpl files to generate source files. Add *.tpl to
dependencies.

Change-Id: Id12fa34e58ef223820528c47e23f9d4bdb2dd3bc
diff --git a/gen_makefile.py b/gen_makefile.py
index 04b16cd..588a37b 100755
--- a/gen_makefile.py
+++ b/gen_makefile.py
@@ -168,7 +168,7 @@
 ### {proj} ###
 
 {proj}_configure_files := $(shell find {src_proj} -name "Makefile.am" -or -name "*.in" -and -not -name "Makefile.in" )
-{proj}_files := $(shell find {src_proj} -name "*.[hc]" -or -name "*.py" -or -name "*.cpp" )
+{proj}_files := $(shell find {src_proj} -name "*.[hc]" -or -name "*.py" -or -name "*.cpp" -or -name "*.tpl" )
 
 .make.{proj}.clone:
 	@echo "\n\n\n===== $@\n"