build: fix building when there is only python3

configure.py

@@ -2121,6 +2121,10 @@ def make_bin_override():
 gyp_args = ['--no-parallel', '-Dconfiguring_node=1']
 gyp_args += ['-Dbuild_type=' + config['BUILDTYPE']]
 
+# always set 'python' variable, otherwise environments that only have python3
+# will fail to run python scripts
+gyp_args += ['-Dpython=' + sys.executable]
+
 if options.use_ninja:
   gyp_args += ['-f', 'ninja-' + flavor]
 elif flavor == 'win' and sys.platform != 'msys':
@@ -2133,10 +2137,6 @@ def make_bin_override():
   os.path.islink('./compile_commands.json') and os.unlink('./compile_commands.json')
   os.symlink('./out/' + config['BUILDTYPE'] + '/compile_commands.json', './compile_commands.json')
 
-# override the variable `python` defined in common.gypi
-if bin_override is not None:
-  gyp_args += ['-Dpython=' + sys.executable]
-
 # pass the leftover non-whitespace positional arguments to GYP
 gyp_args += [arg for arg in args if not str.isspace(arg)]
 

tools/v8_gypfiles/toolchain.gypi

@@ -41,7 +41,7 @@
     'has_valgrind%': 0,
     'coverage%': 0,
     'v8_target_arch%': '<(target_arch)',
-    'v8_host_byteorder%': '<!(python -c "import sys; print(sys.byteorder)")',
+    'v8_host_byteorder%': '<!(<(python) -c "import sys; print(sys.byteorder)")',
     'force_dynamic_crt%': 0,
 
     # Setting 'v8_can_use_vfp32dregs' to 'true' will cause V8 to use the VFP