Backport the master FindBOTAN.cmake, to find botan 2.0 as well

ref #3245

louloulibs/cmake/Modules/FindBOTAN.cmake

@@ -15,21 +15,29 @@
 #
 # This file is in the public domain
 
-find_path(BOTAN_INCLUDE_DIRS NAMES botan/botan.h
-  PATH_SUFFIXES botan-1.11
-  DOC "The botan include directory")
+include(FindPkgConfig)
 
-find_library(BOTAN_LIBRARIES NAMES botan botan-1.11
-  DOC "The botan library")
+pkg_check_modules(BOTAN botan-2)
+pkg_check_modules(BOTAN botan-1.11)
 
-# Use some standard module to handle the QUIETLY and REQUIRED arguments, and
-# set BOTAN_FOUND to TRUE if these two variables are set.
-include(FindPackageHandleStandardArgs)
-find_package_handle_standard_args(BOTAN REQUIRED_VARS BOTAN_LIBRARIES BOTAN_INCLUDE_DIRS)
+if(NOT BOTAN_FOUND)
+  find_path(BOTAN_INCLUDE_DIRS NAMES botan/botan.h
+      PATH_SUFFIXES botan-2 botan-1.11
+      DOC "The botan include directory")
 
-if(BOTAN_FOUND)
-  set(BOTAN_LIBRARY ${BOTAN_LIBRARIES})
-  set(BOTAN_INCLUDE_DIR ${BOTAN_INCLUDE_DIRS})
+  find_library(BOTAN_LIBRARIES NAMES botan botan-2 botan-1.11
+      DOC "The botan library")
+
+  # Use some standard module to handle the QUIETLY and REQUIRED arguments, and
+  # set BOTAN_FOUND to TRUE if these two variables are set.
+  include(FindPackageHandleStandardArgs)
+  find_package_handle_standard_args(BOTAN REQUIRED_VARS BOTAN_LIBRARIES BOTAN_INCLUDE_DIRS)
+
+  if(BOTAN_FOUND)
+    set(BOTAN_LIBRARY ${BOTAN_LIBRARIES} CACHE INTERNAL "")
+    set(BOTAN_INCLUDE_DIR ${BOTAN_INCLUDE_DIRS} CACHE INTERNAL "")
+    set(BOTAN_FOUND ${BOTAN_FOUND} CACHE INTERNAL "")
+  endif()
 endif()
 
 mark_as_advanced(BOTAN_INCLUDE_DIRS BOTAN_LIBRARIES)