configure.ac: use AX_SUBDIRS_CONFIGURE; don't alter ac_configure_args

Altering ac_configure_args to configure libsecp256k1 with options
differing from those of libwally-core causes issues if the wally
Makefile is out of date and needs to call autoreconf etc to
regenerate itself. The secp arguments are passed back to the top
level configure which changes and possibly breaks the original
configuration.

Instead, import and use AX_SUBDIRS_CONFIGURE from the autoconf-archive
which supports sub-confiration with bespoke arguments.

Because autoreconf does not recurse into subdirectories named by
AX_SUBDIRS_CONFIGURE, we lose the automagic Autotools (re)generation in
src/secp256k1, so add an explicit call to src/secp256k1/autogen.sh in
tools/autogen.sh.

configure.ac

@@ -407,8 +407,7 @@ export ARFLAGS
 export AR_FLAGS
 export LD
 export LDFLAGS
-ac_configure_args="${ac_configure_args} --disable-shared --with-pic --enable-experimental --enable-module-ecdh --enable-module-recovery --enable-module-ecdsa-s2c --enable-module-rangeproof --enable-module-surjectionproof --enable-module-whitelist --enable-module-generator --enable-module-extrakeys --enable-module-schnorrsig ${secp256k1_test_opt} --enable-exhaustive-tests=no --enable-benchmark=no --disable-dependency-tracking ${secp_asm}"
-AC_CONFIG_SUBDIRS([src/secp256k1])
 
+AX_SUBDIRS_CONFIGURE([src/secp256k1], [[--disable-shared], [--enable-static], [--with-pic], [--enable-experimental], [--enable-module-ecdh], [--enable-module-recovery], [--enable-module-ecdsa-s2c], [--enable-module-rangeproof], [--enable-module-surjectionproof], [--enable-module-whitelist], [--enable-module-generator], [--enable-module-extrakeys], [--enable-module-schnorrsig], [$secp256k1_test_opt], [--enable-exhaustive-tests=no], [--enable-benchmark=no], [--disable-dependency-tracking], [$secp_asm]])
 
 AC_OUTPUT

setup.py

@@ -3,8 +3,9 @@
 import copy, os, platform, shutil
 import distutils.sysconfig
 
-CONFIGURE_ARGS = '--enable-swig-python --enable-python-manylinux'
-CONFIGURE_ARGS += ' --disable-swig-java --disable-tests --disable-dependency-tracking'
+CONFIGURE_ARGS = ['--disable-shared', '--enable-static', '--with-pic',
+    '--enable-swig-python', '--enable-python-manylinux',
+    '--disable-swig-java', '--disable-tests', '--disable-dependency-tracking']
 
 distutils_env = distutils.sysconfig.get_config_vars()
 configure_env = copy.deepcopy(os.environ)
@@ -26,11 +27,11 @@
     if is_x86 and not is_native:
         # We are cross-compiling or compiling a univeral2 binary.
         # Configure our source code as a cross compile to make the build work
-        CONFIGURE_ARGS += ' --host x86_64-apple-darwin'
+        CONFIGURE_ARGS += ['--host', 'x86_64-apple-darwin']
         arch = 'universal2' if len(archs) > 1 else archs[0]
-        CONFIGURE_ARGS += ' --target {}-apple-macos'.format(arch)
+        CONFIGURE_ARGS += ['--target', '{}-apple-macos'.format(arch)]
         if len(archs) > 1:
-            CONFIGURE_ARGS += ' --with-asm=no'
+            CONFIGURE_ARGS += ['--with-asm=no']
         if 'PY_CFLAGS' in distutils_env:
             configure_env['CFLAGS'] = distutils_env['PY_CFLAGS']
             configure_env['LDFLAGS'] = distutils_env['PY_LDFLAGS']
@@ -40,18 +41,17 @@
     # then build using the standard Python ext module machinery.
     # (Windows requires source generation to be done separately).
     import multiprocessing
-    import os
     import subprocess
 
     abs_path = os.path.dirname(os.path.abspath(__file__)) + '/'
 
-    def call(cmd):
-        subprocess.check_call(cmd.split(' '), cwd=abs_path, env=configure_env)
+    def call(args):
+        subprocess.check_call(args, cwd=abs_path, env=configure_env)
 
-    call('./tools/cleanup.sh')
-    call('./tools/autogen.sh')
-    call('./configure {}'.format(CONFIGURE_ARGS))
-    call('make -j{}'.format(multiprocessing.cpu_count()))
+    call(['./tools/cleanup.sh'])
+    call(['./tools/autogen.sh'])
+    call(['./configure'] + CONFIGURE_ARGS)
+    call(['make', '-j{}'.format(multiprocessing.cpu_count())])
 
 define_macros=[
     ('SWIG_PYTHON_BUILD', None),

tools/autogen.sh

@@ -8,3 +8,7 @@ if uname | grep "Darwin" >/dev/null 2>&1; then
         done
     done
 fi
+
+if [ -x src/secp256k1/autogen.sh ] ; then
+    cd src/secp256k1 && ./autogen.sh
+fi