[PATCH mtd-utils] ubifs-utils: link libmissing.a in case execinfo.h isn't present

[Ross Burton]

On musl execinfo.h doesn't exist, but ubifs-utils uses backtrace() when
reporting errors.  This results in build failures under musl.

Handily, libmissing.a already exists with a stub implementation of
backtrace().

Guard the execinfo.h include and if it isn't available instead include
libmissing.h, and link to libmissing.a to provide backtrace() if needed.

Signed-off-by: Ross Burton <ross.burton at arm.com>
---
 ubifs-utils/Makemodule.am | 4 ++--
 ubifs-utils/common/defs.h | 5 ++++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/ubifs-utils/Makemodule.am b/ubifs-utils/Makemodule.am
index 21ba059..f84569a 100644
--- a/ubifs-utils/Makemodule.am
+++ b/ubifs-utils/Makemodule.am
@@ -72,7 +72,7 @@ mkfs_ubifs_SOURCES = \
 	ubifs-utils/mkfs.ubifs/mkfs.ubifs.c
 
 mkfs_ubifs_LDADD = libmtd.a libubi.a $(ZLIB_LIBS) $(LZO_LIBS) $(ZSTD_LIBS) $(UUID_LIBS) $(LIBSELINUX_LIBS) $(OPENSSL_LIBS) \
-		   $(DUMP_STACK_LD) $(ASAN_LIBS) -lm -lpthread
+		   $(DUMP_STACK_LD) $(ASAN_LIBS) -lm -lpthread libmissing.a
 mkfs_ubifs_CPPFLAGS = $(AM_CPPFLAGS) $(ZLIB_CFLAGS) $(LZO_CFLAGS) $(ZSTD_CFLAGS) $(UUID_CFLAGS) $(LIBSELINUX_CFLAGS) \
 	-I$(top_srcdir)/ubi-utils/include -I$(top_srcdir)/ubifs-utils/common -I $(top_srcdir)/ubifs-utils/libubifs
 
@@ -90,7 +90,7 @@ fsck_ubifs_SOURCES = \
 	ubifs-utils/fsck.ubifs/handle_disconnected.c
 
 fsck_ubifs_LDADD = libmtd.a libubi.a $(ZLIB_LIBS) $(LZO_LIBS) $(ZSTD_LIBS) $(UUID_LIBS) $(LIBSELINUX_LIBS) $(OPENSSL_LIBS) \
-		   $(DUMP_STACK_LD) $(ASAN_LIBS) -lm -lpthread
+		   $(DUMP_STACK_LD) $(ASAN_LIBS) -lm -lpthread libmissing.a
 fsck_ubifs_CPPFLAGS = $(AM_CPPFLAGS) $(ZLIB_CFLAGS) $(LZO_CFLAGS) $(ZSTD_CFLAGS) $(UUID_CFLAGS) $(LIBSELINUX_CFLAGS) \
 	-I$(top_srcdir)/ubi-utils/include -I$(top_srcdir)/ubifs-utils/common -I $(top_srcdir)/ubifs-utils/libubifs \
 	-I$(top_srcdir)/ubifs-utils/fsck.ubifs
diff --git a/ubifs-utils/common/defs.h b/ubifs-utils/common/defs.h
index 7ff1771..d5edbf6 100644
--- a/ubifs-utils/common/defs.h
+++ b/ubifs-utils/common/defs.h
@@ -13,8 +13,11 @@
 #include <errno.h>
 #include <time.h>
 #include <assert.h>
+#if HAVE_EXECINFO_H
 #include <execinfo.h>
-
+#else
+#include "libmissing.h"
+#endif
 #include "ubifs.h"
 
 /* common.h requires the PROGRAM_NAME macro */
-- 
2.43.0