build: Use secp objects directly when linking

For straight libwallycore.so builds, this avoids issues with adding ar files
containing universal binaries to an existing ar file, which current tooling
does not support.

Author: jgriffiths

configure.ac

@@ -171,11 +171,6 @@ AC_SUBST([NOOPT_CFLAGS])
 AC_SUBST([NOALIAS_CFLAGS])
 AC_SUBST([NOBUILTIN_CFLAGS])
 
-# Under OSX the compiler accepts this flag but the linker then fails.
-if test "x$is_osx" != "xyes"; then
-    AX_CHECK_COMPILE_FLAG([-Wl,--whole-archive], [whole_archive=yes])
-fi
-
 # SWIG versions vary in generated code quality; skip warnings
 SWIG_WARN_CFLAGS="-fno-strict-aliasing"
 AX_CHECK_COMPILE_FLAG([-Wno-shadow], [SWIG_WARN_CFLAGS="$SWIG_WARN_CFLAGS -Wno-shadow"])
@@ -236,30 +231,6 @@ if test "x$ac_have_pthread" == "xyes"; then
     AC_CHECK_HEADERS([asm/page.h])
 fi
 
-#
-# libsecp256k1
-#
-# FIXME: This is needed to force libtool to use all object files from secp.
-#        We can only build secp properly by recursively invoking
-#        configure/make, and can't include it as a noinst_ library. Libtool
-#        assumes that such libraries will be installed along with our library
-#        target and so won't force all object files in the library to be
-#        included in ours - despite the fact that we are making a shared
-#        library and linking to a static one. This is broken and we work
-#        around it by hacking the whole-archive flags into the _LDADD variable
-#        for wallycore.
-#        Because automake tries to police its users very strictly and fails
-#        hard when flags are passed in this way, we have to substitute the
-#        flags here.
-#        Because libtool both intercepts -Wl and arbitrarily re-orders its
-#        command line inputs, we have to concoct a single expression to
-#        enforce linking that cannot be split, hence the below expression.
-LIBADD_SECP256K1="secp256k1/.libs/libsecp256k1.a"
-if test "x$whole_archive" == "xyes"; then
-    LIBADD_SECP256K1="-Wl,--whole-archive,secp256k1/.libs/libsecp256k1.a,--no-whole-archive"
-fi
-AC_SUBST([LIBADD_SECP256K1])
-
 #
 # Python facilities
 #

src/Makefile.am

@@ -236,7 +236,7 @@ endif
 endif # SHARED_BUILD_ENABLED
 
 libwallycore_la_CFLAGS = -I$(top_srcdir) -I$(srcdir)/ccan -DWALLY_CORE_BUILD=1 $(AM_CFLAGS)
-libwallycore_la_LIBADD = $(LIBADD_SECP256K1) $(noinst_LTLIBRARIES)
+libwallycore_la_LIBADD = secp256k1/src/libsecp256k1_la-secp256k1.o secp256k1/src/libsecp256k1_precomputed_la-precomputed_ecmult_gen.o secp256k1/src/libsecp256k1_precomputed_la-precomputed_ecmult.o $(noinst_LTLIBRARIES)
 
 SUBDIRS = secp256k1