ci, build: replace CI workflows with thin wrappers

Splits the repository so C++ source stays on master and CI scripts,
docs, and examples move to the support branch. Master's CI workflows
become thin wrappers that delegate to the reusable workflows on the
support branch.

GitHub Actions changes:
- ci.yml, bitcoin-core-ci.yml: replaced with thin wrappers that call
  the corresponding reusable workflows on the support branch.

CMakeLists.txt:
- Remove add_subdirectory(example): example/ moves to the support
  branch and is built from support's own CMakeLists.txt.

cmake/TargetCapnpSources.cmake:
- Fix build-side include path computation to anchor on
  CMAKE_CURRENT_SOURCE_DIR/BINARY_DIR instead of the top-level
  CMAKE_SOURCE_DIR/BINARY_DIR. The old code computed a relative path
  from the project root to include_prefix and appended it to
  CMAKE_BINARY_DIR, which breaks when include_prefix lies outside
  CMAKE_SOURCE_DIR (as happens when master is built as a subdirectory
  of the support branch project).
- Update docstring and example to use CMAKE_CURRENT_SOURCE_DIR.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ryanofsky

.github/workflows/bitcoin-core-ci.yml

@@ -0,0 +1,14 @@
+name: Bitcoin Core CI
+
+on:
+  push:
+  pull_request:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  bitcoin-core-ci:
+    uses: bitcoin-core/libmultiprocess/.github/workflows/bitcoin-core-ci.yml@support
+    secrets: inherit

.github/workflows/ci.yml

@@ -0,0 +1,10 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  ci:
+    uses: bitcoin-core/libmultiprocess/.github/workflows/ci.yml@support
+    secrets: inherit

CMakeLists.txt

@@ -261,6 +261,4 @@ add_custom_target(install-lib
   VERBATIM)
 add_dependencies(install-lib multiprocess)
 
-# Example and test subdirectories
-add_subdirectory(example EXCLUDE_FROM_ALL)
 add_subdirectory(test EXCLUDE_FROM_ALL)

cmake/TargetCapnpSources.cmake

@@ -27,10 +27,8 @@ Arguments:
 
       #include <schema.capnp.h>
 
-    The specified include_prefix should be ${CMAKE_SOURCE_DIR} or a
-    subdirectory of it to include files relative to the project root. It can
-    be ${CMAKE_CURRENT_SOURCE_DIR} to include files relative to the current
-    source directory.
+    Pass ${CMAKE_CURRENT_SOURCE_DIR} or a subdirectory of it to include files
+    relative to the current source directory (the typical usage).
 
 Additional Unnamed Arguments:
 
@@ -46,9 +44,9 @@ Optional Keyword Arguments:
 Example:
   # Assuming `my_library` is a target and `lib/` contains `.capnp` schema
   # files with imports from `include/`.
-  target_capnp_sources(my_library "${CMAKE_SOURCE_DIR}"
+  target_capnp_sources(my_library "${CMAKE_CURRENT_SOURCE_DIR}"
                        lib/schema1.capnp lib/schema2.capnp
-                       IMPORT_PATHS ${CMAKE_SOURCE_DIR}/include)
+                       IMPORT_PATHS ${CMAKE_CURRENT_SOURCE_DIR}/include)
 
 #]=]
 
@@ -98,8 +96,8 @@ function(target_capnp_sources target include_prefix)
 
   # Translate include_prefix from a source path to a binary path and add it as a
   # target include directory.
-  set(build_include_prefix ${CMAKE_BINARY_DIR})
-  file(RELATIVE_PATH relative_path ${CMAKE_SOURCE_DIR} ${include_prefix})
+  set(build_include_prefix ${CMAKE_CURRENT_BINARY_DIR})
+  file(RELATIVE_PATH relative_path ${CMAKE_CURRENT_SOURCE_DIR} ${include_prefix})
   if(relative_path)
     string(APPEND build_include_prefix "/" "${relative_path}")
   endif()