Change python.module soabi's default value to true

Author: Freed-Wu

tests/projects/python/pybind/example/xmake.lua

@@ -2,7 +2,7 @@ add_rules("mode.release", "mode.debug")
 add_requires("pybind11")
 
 target("example")
-    add_rules("python.module")
+    add_rules("python.module", {soabi = false})
     add_files("src/*.cpp")
     add_packages("pybind11")
     set_languages("c++11")

tests/projects/python/pybind/example_with_soabi/xmake.lua

@@ -2,7 +2,7 @@ add_rules("mode.release", "mode.debug")
 add_requires("pybind11")
 
 target("example")
-    add_rules("python.module", {soabi = true})
+    add_rules("python.module")
     add_files("src/*.cpp")
     add_packages("pybind11")
     set_languages("c++11")

xmake/rules/python/module/xmake.lua

@@ -25,7 +25,7 @@ rule("python.module")
         target:set("prefixname", "")
         target:add("runenvs", "PYTHONPATH", target:targetdir())
         local soabi = target:extraconf("rules", "python.module", "soabi")
-        if soabi then
+        if soabi == nil or soabi then
             import("lib.detect.find_tool")
             local python = assert(find_tool("python3"), "python not found!")
             local result = try { function() return os.iorunv(python.program, {"-c", "import sysconfig; print(sysconfig.get_config_var('EXT_SUFFIX'))"}) end}