[C++] Make git-dependent definitions internal

Exposing the ARROW_GIT_ID and ARROW_GIT_DESCRIPTION preprocessor variables in our public headers tends to make incremental builds less efficient, since those values change very often during development.

Also, these values don't need to be preprocessor variables since they're just strings: you can't write useful `#if` directives with them. Instead, they can be inspected using `GetBuildInfo()`.

cpp/cmake_modules/ThirdpartyToolchain.cmake

@@ -5348,9 +5348,3 @@ if(ARROW_WITH_UCX)
 endif()
 
 message(STATUS "All bundled static libraries: ${ARROW_BUNDLED_STATIC_LIBS}")
-
-# Write out the package configurations.
-
-configure_file("src/arrow/util/config.h.cmake" "src/arrow/util/config.h" ESCAPE_QUOTES)
-install(FILES "${ARROW_BINARY_DIR}/src/arrow/util/config.h"
-        DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/arrow/util")

cpp/src/arrow/CMakeLists.txt

@@ -351,6 +351,12 @@ macro(append_runtime_avx512_src SRCS SRC)
   endif()
 endmacro()
 
+# Write out compile-time configuration constants
+configure_file("util/config.h.cmake" "util/config.h" ESCAPE_QUOTES)
+configure_file("util/config_internal.h.cmake" "util/config_internal.h" ESCAPE_QUOTES)
+install(FILES "${CMAKE_CURRENT_BINARY_DIR}/util/config.h"
+        DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/arrow/util")
+
 set(ARROW_SRCS
     builder.cc
     buffer.cc

cpp/src/arrow/config.cc

@@ -20,6 +20,7 @@
 #include <cstdint>
 
 #include "arrow/util/config.h"
+#include "arrow/util/config_internal.h"
 #include "arrow/util/cpu_info.h"
 #include "arrow/vendored/datetime.h"
 

cpp/src/arrow/util/config.h.cmake

@@ -31,9 +31,6 @@
 
 #define ARROW_BUILD_TYPE "@UPPERCASE_BUILD_TYPE@"
 
-#define ARROW_GIT_ID "@ARROW_GIT_ID@"
-#define ARROW_GIT_DESCRIPTION "@ARROW_GIT_DESCRIPTION@"
-
 #define ARROW_PACKAGE_KIND "@ARROW_PACKAGE_KIND@"
 
 #cmakedefine ARROW_COMPUTE

cpp/src/arrow/util/config_internal.h.cmake

@@ -0,0 +1,22 @@
+// 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.
+
+// These variables are not exposed as they can make compilation caching
+// and increment builds less efficient.
+
+#define ARROW_GIT_ID "@ARROW_GIT_ID@"
+#define ARROW_GIT_DESCRIPTION "@ARROW_GIT_DESCRIPTION@"