use check_type_size instead of built-in CMAKE_SIZEOF_VOID_P to fix 64 bit

detection on some Suse machines (patch from Bastien)

CMakeLists.txt

@@ -137,6 +137,16 @@ macro(find_all_libraries VARNAME LISTNAME SUFFIX)
   endif(NUM_FOUND_LIBRARIES LESS NUM_LIST)
 endmacro(find_all_libraries)
 
+# check if the machine is 64 bits (this is more reliable than using
+# CMAKE_SIZEOF_VOID_P, which does not seem to work e.g. on some Suse
+# machines)
+include(CheckTypeSize)
+check_type_size("void*" SIZEOF_VOID_P)
+if(SIZEOF_VOID_P EQUAL 8)
+  set(HAVE_64BIT_SIZE_T TRUE)
+  list(APPEND CONFIG_OPTIONS "Have64BitSizeT")
+endif(SIZEOF_VOID_P EQUAL 8)
+
 if(ENABLE_BLAS_LAPACK)
   if(MSVC)
     # on Windows with Visual C++ try really hard to find blas/lapack
@@ -145,11 +155,11 @@ if(ENABLE_BLAS_LAPACK)
     # get the reference blas/lapack libs (useful for users with no
     # Fortran compiler and no MKL license, who can just download our
     # precompiled "gmsh-dep" package)
-    if(CMAKE_SIZEOF_VOID_P EQUAL 8)
+    if(HAVE_64BIT_SIZE_T)
       set(MKL_PATH em64t/lib)
-    else(CMAKE_SIZEOF_VOID_P EQUAL 8)
+    else(HAVE_64BIT_SIZE_T)
       set(MKL_PATH ia32/lib)
-    endif(CMAKE_SIZEOF_VOID_P EQUAL 8)
+    endif(HAVE_64BIT_SIZE_T)
     set(MKL_LIBS_REQUIRED libguide40 mkl_intel_c mkl_intel_thread mkl_core)
     find_all_libraries(LAPACK_LIBRARIES MKL_LIBS_REQUIRED ${MKL_PATH})
     if(LAPACK_LIBRARIES)
@@ -168,11 +178,11 @@ if(ENABLE_BLAS_LAPACK)
   elseif(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
     # on Linux also try to find the Intel MKL without a Fortran
     # compiler
-    if(CMAKE_SIZEOF_VOID_P EQUAL 8)
+    if(HAVE_64BIT_SIZE_T)
       set(MKL_PATH lib/em64t)
-    else(CMAKE_SIZEOF_VOID_P EQUAL 8)
+    else(HAVE_64BIT_SIZE_T)
       set(MKL_PATH lib/32)
-    endif(CMAKE_SIZEOF_VOID_P EQUAL 8)
+    endif(HAVE_64BIT_SIZE_T)
     set(MKL_LIBS_REQUIRED mkl_gf_lp64 iomp5 mkl_gnu_thread mkl_core)
     find_all_libraries(LAPACK_LIBRARIES MKL_LIBS_REQUIRED ${MKL_PATH})
     if(LAPACK_LIBRARIES)
@@ -524,6 +534,9 @@ if(ENABLE_OCC)
       list(APPEND CONFIG_OPTIONS "OpenCascade")
       list(APPEND EXTERNAL_LIBRARIES ${OCC_LIBS})
       list(APPEND EXTERNAL_INCLUDES ${OCC_INC})
+      if(HAVE_64BIT_SIZE_T)
+        add_definitions(-D_OCC64)
+      endif(HAVE_64BIT_SIZE_T)
       if(CYGWIN)
         list(APPEND EXTERNAL_LIBRARIES "winspool")
       elseif(MSVC)
@@ -542,14 +555,6 @@ if(ENABLE_OSMESA)
   endif(OSMESA_LIB)
 endif(ENABLE_OSMESA)
 
-if(CMAKE_SIZEOF_VOID_P EQUAL 8)
-  set(HAVE_64BIT_SIZE_T TRUE)
-  list(APPEND CONFIG_OPTIONS "Have64BitSizeT")
-  if(HAVE_OCC)
-    add_definitions(-D_OCC64)
-  endif(HAVE_OCC)
-endif(CMAKE_SIZEOF_VOID_P EQUAL 8)
-
 include(CheckFunctionExists)
 check_function_exists(vsnprintf HAVE_VSNPRINTF)
 if(NOT HAVE_VSNPRINTF)