Added support for system PCRE2

This will allow system PCRE2 to be used instead of always using the bundled one.

CMakeLists.txt

@@ -42,9 +42,15 @@ find_package(Git)
 find_package(CURL) 
 find_package(RabbitMQ)
 
-# Build PCRE2
+# Find or build PCRE2
 # Read BuildPCRE2 for details about how to add pcre2 as a dependency to a target
-include(cmake/BuildPCRE2.cmake)
+find_package(PCRE2)
+if(NOT PCRE2_FOUND)
+  message(STATUS "Using bundled PCRE2 library")
+  include(cmake/BuildPCRE2.cmake)
+endif()
+
+include_directories(${PCRE2_INCLUDE_DIRS})
 
 # If the connector was not found, download and build it from source
 if(NOT MARIADB_CONNECTOR_FOUND)

cmake/BuildPCRE2.cmake

@@ -14,5 +14,6 @@ ExternalProject_Add(pcre2 SOURCE_DIR ${CMAKE_SOURCE_DIR}/pcre2/
   BUILD_COMMAND make
   INSTALL_COMMAND "")
 
-include_directories(${CMAKE_BINARY_DIR}/pcre2/)
-set(PCRE2_LIBRARIES ${CMAKE_BINARY_DIR}/pcre2/libpcre2-8.a CACHE INTERNAL "")
+set(PCRE2_INCLUDE_DIRS ${CMAKE_BINARY_DIR}/pcre2/ CACHE PATH "PCRE2 headers" FORCE)
+set(PCRE2_LIBRARIES ${CMAKE_BINARY_DIR}/pcre2/libpcre2-8.a CACHE PATH "PCRE2 libraries" FORCE)
+set(PCRE2_FOUND TRUE CACHE BOOL "Found PCRE2 libraries" FORCE)

cmake/FindPCRE2.cmake

@@ -0,0 +1,17 @@
+# This CMake file tries to find the Perl regular expression libraries
+# The following variables are set:
+# PCRE2_FOUND - System has the PCRE library
+# PCRE2_LIBRARIES - The PCRE library file
+# PCRE2_INCLUDE_DIRS - The folder with the PCRE headers
+
+find_library(PCRE2_LIBRARIES NAMES pcre2 pcre2-8)
+find_path(PCRE2_INCLUDE_DIRS pcre2.h)
+if(PCRE2_LIBRARIES AND PCRE2_INCLUDE_DIRS)
+  message(STATUS "PCRE2 libs: ${PCRE2_LIBRARIES}")
+  message(STATUS "PCRE2 include directory: ${PCRE2_INCLUDE_DIRS}")
+  set(PCRE2_FOUND TRUE CACHE BOOL "Found PCRE2 libraries" FORCE)
+  add_custom_target(pcre2)
+else()
+  set(PCRE2_FOUND FALSE CACHE BOOL "Found PCRE2 libraries" FORCE)
+  message(STATUS "PCRE2 library not found.")
+endif()