common/amount: new types struct amount_msat and struct amount_sat.

They're generally used pass-by-copy (unusual for C structs, but
convenient they're basically u64) and all possibly problematic
operations return WARN_UNUSED_RESULT bool to make you handle the
over/underflow cases.

The new #include in json.h means we bolt11.c sees the amount.h definition
of MSAT_PER_BTC, so delete its local version.

Signed-off-by: Rusty Russell <[email protected]>

channeld/Makefile

@@ -33,8 +33,9 @@ ALL_GEN_HEADERS += $(LIGHTNINGD_CHANNEL_HEADERS_GEN)
 
 # Common source we use.
 CHANNELD_COMMON_OBJS :=				\
+	common/amount.o				\
 	common/base32.o				\
-	common/bip32.o			\
+	common/bip32.o				\
 	common/channel_config.o			\
 	common/crypto_state.o			\
 	common/crypto_sync.o			\

channeld/test/run-commit_tx.c

@@ -12,6 +12,7 @@ static bool print_superverbose;
 #include <ccan/array_size/array_size.h>
 #include <ccan/err/err.h>
 #include <ccan/str/hex/hex.h>
+#include <common/amount.h>
 #include <common/key_derive.h>
 #include <common/status.h>
 

channeld/test/run-full_channel.c

@@ -7,11 +7,15 @@
 #include <bitcoin/pubkey.h>
 #include <ccan/err/err.h>
 #include <ccan/str/hex/hex.h>
+#include <common/amount.h>
 #include <common/sphinx.h>
 #include <common/type_to_string.h>
 #include <stdio.h>
 #include <wally_core.h>
 
+/* AUTOGENERATED MOCKS START */
+/* AUTOGENERATED MOCKS END */
+
 void status_fmt(enum log_level level UNUSED, const char *fmt, ...)
 {
 	va_list ap;

cli/test/run-large-input.c

@@ -1,4 +1,5 @@
 #include <assert.h>
+#include <common/amount.h>
 #include <fcntl.h>
 #include <sys/socket.h>
 #include <sys/stat.h>

closingd/Makefile

@@ -42,6 +42,7 @@ $(LIGHTNINGD_CLOSING_OBJS): $(LIGHTNINGD_HEADERS)
 
 # Common source we use.
 CLOSINGD_COMMON_OBJS :=				\
+	common/amount.o				\
 	common/base32.o				\
 	common/bip32.o				\
 	common/close_tx.o			\

common/Makefile

@@ -1,4 +1,5 @@
 COMMON_SRC_NOGEN :=				\
+	common/amount.c				\
 	common/base32.c				\
 	common/bech32.c				\
 	common/bech32_util.c			\