Set up for Bazel module builds. (#1597)

* Set up for Bazel module builds.

Note: the MODULE.bazel is copied from https://github.com/bazelbuild/bazel-central-registry/blob/main/modules/jsoncpp/1.9.6/MODULE.bazel

* More tweaks to .gitignore

Author: bcsgh

.gitignore

@@ -55,3 +55,7 @@ compile_commands.json
 
 # temps
 /version
+
+# Bazel output paths
+/bazel-*
+/MODULE.bazel.lock

CMakeLists.txt

@@ -55,12 +55,13 @@ endif()
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 
 project(jsoncpp
-        # Note: version must be updated in three places when doing a release. This
+        # Note: version must be updated in four places when doing a release. This
         # annoying process ensures that amalgamate, CMake, and meson all report the
         # correct version.
         # 1. ./meson.build
         # 2. ./include/json/version.h
         # 3. ./CMakeLists.txt
+        # 4. ./MODULE.bazel
         # IMPORTANT: also update the PROJECT_SOVERSION!!
         VERSION 1.9.7 # <major>[.<minor>[.<patch>[.<tweak>]]]
         LANGUAGES CXX)

MODULE.bazel

@@ -0,0 +1,14 @@
+module(
+    name = "jsoncpp",
+
+    # Note: version must be updated in four places when doing a release. This
+    # annoying process ensures that amalgamate, CMake, and meson all report the
+    # correct version.
+    # 1. /meson.build
+    # 2. /include/json/version.h
+    # 3. /CMakeLists.txt
+    # 4. /MODULE.bazel
+    # IMPORTANT: also update the SOVERSION!!
+    version = "1.9.7",
+    compatibility_level = 1,
+)

include/json/version.h

@@ -1,12 +1,13 @@
 #ifndef JSON_VERSION_H_INCLUDED
 #define JSON_VERSION_H_INCLUDED
 
-// Note: version must be updated in three places when doing a release. This
+// Note: version must be updated in four places when doing a release. This
 // annoying process ensures that amalgamate, CMake, and meson all report the
 // correct version.
 // 1. /meson.build
 // 2. /include/json/version.h
 // 3. /CMakeLists.txt
+// 4. /MODULE.bazel
 // IMPORTANT: also update the SOVERSION!!
 
 #define JSONCPP_VERSION_STRING "1.9.7"

meson.build

@@ -2,12 +2,13 @@ project(
   'jsoncpp',
   'cpp',
 
-  # Note: version must be updated in three places when doing a release. This
+  # Note: version must be updated in four places when doing a release. This
   # annoying process ensures that amalgamate, CMake, and meson all report the
   # correct version.
   # 1. /meson.build
   # 2. /include/json/version.h
   # 3. /CMakeLists.txt
+  # 4. /MODULE.bazel
   # IMPORTANT: also update the SOVERSION!!
   version : '1.9.7',
   default_options : [