damus-c: add bolt11 parser from CLN

We'll need this for our lightning invoice view

Signed-off-by: William Casarin <jb55@jb55.com>

damus-c/config.h

@@ -0,0 +1,18 @@
+/* Generated by CCAN configurator */
+#ifndef CCAN_CONFIG_H
+#define CCAN_CONFIG_H
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE /* Always use GNU extensions. */
+#endif
+#define CCAN_COMPILER "cc"
+#define CCAN_CFLAGS "-g3 -ggdb -Wall -Wundef -Wmissing-prototypes -Wmissing-declarations -Wstrict-prototypes -Wold-style-definition"
+#define CCAN_OUTPUT_EXE_CFLAG "-o"
+
+#define HAVE_CCAN 1
+#define HAVE_UNALIGNED_ACCESS 1
+#define HAVE_TYPEOF 1
+#define HAVE_BIG_ENDIAN 0
+#define HAVE_BYTESWAP_H 0
+#define HAVE_BSWAP_64 0
+#define HAVE_LITTLE_ENDIAN 1
+#endif /* CCAN_CONFIG_H */