add missing inline keywords (compilation error) spotted by timvdm

Eigen/src/Core/MatrixStorage.h

@@ -37,8 +37,10 @@ template <typename T, int Size, int MatrixOptions,
 
   ei_matrix_array()
   {
+    #ifndef EIGEN_DISABLE_UNALIGNED_ARRAY_ASSERT
     ei_assert((reinterpret_cast<size_t>(array) & 0xf) == 0
               && "this assertion is explained here: http://eigen.tuxfamily.org/api/UnalignedArrayAssert.html  **** READ THIS WEB PAGE !!! ****");
+    #endif
   }
 };