GH-47967: [C++] Update Meson Configuration with SafeInt Changes (#47968)

### Rationale for this change

This retains feature parity with CMake

### What changes are included in this PR?

Adds a Meson configuration file for the vendored safeint headers

### Are these changes tested?

Yes

### Are there any user-facing changes?

No
* GitHub Issue: #47967

Authored-by: Will Ayd <[email protected]>
Signed-off-by: Sutou Kouhei <[email protected]>

Author: WillAyd

cpp/src/arrow/vendored/meson.build

@@ -24,4 +24,5 @@ subdir('datetime')
 subdir('double-conversion')
 subdir('pcg')
 subdir('portable-snippets')
+subdir('safeint')
 subdir('xxhash')

cpp/src/arrow/vendored/portable-snippets/meson.build

@@ -15,7 +15,4 @@
 # specific language governing permissions and limitations
 # under the License.
 
-install_headers(
-    ['debug-trap.h', 'safe-math.h'],
-    subdir: 'arrow/vendored/portable-snippets',
-)
+install_headers(['debug-trap.h'], subdir: 'arrow/vendored/portable-snippets')

cpp/src/arrow/vendored/safeint/meson.build

@@ -0,0 +1,21 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+install_headers(
+    ['safe_math.h', 'safe_math_impl.h'],
+    subdir: 'arrow/vendored/safeint',
+)