makefile: add all headers to the tarball

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
diff --git a/Makefile.am b/Makefile.am
index f4f0912..9f49ce6 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -44,12 +44,15 @@
 	scons \
 	SConstruct
 
-noinst_HEADERS =					\
-	include/c99_compat.h				\
-	include/c99					\
-	include/c11					\
-	include/D3D9					\
-	include/HaikuGL					\
+noinst_HEADERS = \
+	include/c99_alloca.h \
+	include/c99_compat.h \
+	include/c99_math.h \
+	include/c99 \
+	include/c11 \
+	include/D3D9 \
+	include/HaikuGL \
+	include/no_extern_c.h \
 	include/pci_ids
 
 # We list some directories in EXTRA_DIST, but don't actually want to include