fix(cppad): build static lib for cppad

this is needed for gcc build and does not break clang build

build-config/cppad/meson.build

@@ -1,21 +1,11 @@
-#cppad_inc = include_directories('include', is_system: true)
-#cppad_dep = declare_dependency(
-#  include_directories: cppad_inc,
-#)
-#
-#message('Registering CppAD headers for installation...')
-#install_subdir('include/cppad', install_dir: get_option('includedir'))
-#message('Done registering CppAD headers for installation!')
-#
-
-
 cppad_cmake_options = cmake.subproject_options()
 
 cppad_cmake_options.add_cmake_defines({
     'cppad_static_lib': 'true',
     'cpp_mas_num_threads': '10',
     'cppad_debug_and_release': 'false',
-    'include_doc': 'false'
+    'include_doc': 'false',
+    'CMAKE_POSITION_INDEPENDENT_CODE': true
 })
 
 cppad_cmake_options.set_install(false)
@@ -25,4 +15,22 @@ cppad_sp = cmake.subproject(
     options: cppad_cmake_options,
 )
 
-cppad_dep = cppad_sp.dependency('cppad_lib').as_system()
+cppad_target = cppad_sp.target('cppad_lib')
+cppad_objs = [cppad_target.extract_all_objects(recursive: true)]
+cppad_incs = cppad_sp.include_directories('cppad_lib')
+
+empty_cppad_file = configure_file(output: 'cppad_dummy_ar.cpp', command: ['echo'], capture: true)
+
+libcppad_static = static_library(
+  'cppad-static',
+  empty_cppad_file,
+  objects: cppad_objs,
+  include_directories: cppad_incs,
+  pic: true,
+  install: false
+)
+
+cppad_dep = declare_dependency(
+  link_with: libcppad_static,
+  include_directories: cppad_incs
+)