CMake: avoid referencing 'EXPAT_FOUND' when 'with_expat' is not set

CMake when using `--warn-uninitialized -Werror=dev` notices that this variable
is being incorrectly referenced when `-Dwith_expat=OFF`:

  CMake Error (dev) at cmake/config_checks.cmake:40 (set):
    uninitialized variable 'EXPAT_FOUND'
  Call Stack (most recent call first):
    CMakeLists.txt:197 (include)

Gitlab: #2291

diff --git a/cmake/config_checks.cmake b/cmake/config_checks.cmake
index 4b9ab3e0c4bb3281dae4968fd6f07e8539cf9ee1..e9a6ed6acf34e37c3fa03471e8ecca8c47c883a3 100644 (file)
--- a/cmake/config_checks.cmake
+++ b/cmake/config_checks.cmake
@@ -37,7 +37,9 @@ check_type_size( intptr_t    INTPTR_T    )
 
 # Library checks
 set( HAVE_ANN       ${ANN_FOUND}        )
-set( HAVE_EXPAT     ${EXPAT_FOUND}      )
+if(with_expat AND EXPAT_FOUND)
+  set(HAVE_EXPAT 1)
+endif()
 set( HAVE_LIBGD     ${GD_FOUND}         )
 set( HAVE_ZLIB      ${ZLIB_FOUND}       )