Detect GNUmakefile too

README.md

@@ -24,7 +24,7 @@ Example usage:
     -----> Compiling with Make
            gcc -o myapp myapp.c
 
-The buildpack will detect your app as C if it has the file `Makefile` in the root.  It will run a `configure` script if it exists in the root of the repository. It will then run `make` to compile the app.
+The buildpack will detect your app as C if it has the file `Makefile` or `GNUmakefile` in the root.  It will run a `configure` script if it exists in the root of the repository. It will then run `make` to compile the app.
 
 Hacking
 -------

bin/detect

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 # bin/detect <build-dir>
 
-if [[ -f $1/Makefile  ||  -f $1/configure ]]; then
+if [[ -f $1/Makefile  ||  -f $1/configure  ||  -f $1/GNUmakefile ]]; then
   echo "C" && exit 0
 else
   echo "no" && exit 1