build: enable Maglev for riscv64

V8's Maglev compiler has supported riscv64 since V8 14.0 (with full
source files in deps/v8/src/maglev/riscv/), but Node.js never wired
it up:

- configure.py excluded riscv64 from maglev_enabled_architectures
- tools/v8_gypfiles/v8.gyp lacked GN-scraper conditions for riscv64
  Maglev sources in both the v8_internal_headers and
  v8_base_without_compiler blocks

This adds riscv64 to both, following the same pattern used for s390x
in #60863 and matching V8's own BUILD.gn which already lists riscv64
alongside arm, arm64, x64, s390x, and ppc64 as Maglev-enabled
architectures.

Refs: nodejs/build#4099
Signed-off-by: Jamie Magee <jamie.magee@gmail.com>

Author: JamieMagee

configure.py

@@ -55,7 +55,7 @@
 valid_mips_float_abi = ('soft', 'hard')
 valid_intl_modes = ('none', 'small-icu', 'full-icu', 'system-icu')
 icu_versions = json.loads((tools_path / 'icu' / 'icu_versions.json').read_text(encoding='utf-8'))
-maglev_enabled_architectures = ('x64', 'arm', 'arm64', 's390x')
+maglev_enabled_architectures = ('x64', 'arm', 'arm64', 's390x', 'riscv64')
 
 # builtins may be removed later if they have been disabled by options
 shareable_builtins = {'undici/undici': 'deps/undici/undici.js',

tools/v8_gypfiles/v8.gyp

@@ -716,6 +716,11 @@
                   '<!@pymod_do_main(GN-scraper "<(V8_ROOT)/BUILD.gn"  "v8_header_set.\\"v8_internal_headers\\".*?v8_enable_maglev.*?v8_current_cpu == \\"ppc64\\".*?sources \\+= ")',
                 ],
               }],
+              ['v8_target_arch=="riscv64"', {
+                'sources': [
+                  '<!@pymod_do_main(GN-scraper "<(V8_ROOT)/BUILD.gn"  "v8_header_set.\\"v8_internal_headers\\".*?v8_enable_maglev.*?v8_current_cpu == \\"riscv64\\".*?sources \\+= ")',
+                ],
+              }],
             ],
           }],
           ['v8_enable_webassembly==1', {
@@ -1185,6 +1190,11 @@
                 '<!@pymod_do_main(GN-scraper "<(V8_ROOT)/BUILD.gn"  "\\"v8_base_without_compiler.*?v8_enable_maglev.*?v8_current_cpu == \\"ppc64\\".*?sources \\+= ")',
               ],
             }],
+            ['v8_target_arch=="riscv64"', {
+              'sources': [
+                '<!@pymod_do_main(GN-scraper "<(V8_ROOT)/BUILD.gn"  "\\"v8_base_without_compiler.*?v8_enable_maglev.*?v8_current_cpu == \\"riscv64\\".*?sources \\+= ")',
+              ],
+            }],
           ],
         }],
         ['v8_enable_webassembly==1', {