Fix -fPIC issue.

cmake/libigl.cmake

@@ -83,10 +83,8 @@ if(MSVC)
   endif()
 endif()
 
-if(BUILD_SHARED_LIBS)
-  # Generate position independent code
-  set_target_properties(igl_common PROPERTIES INTERFACE_POSITION_INDEPENDENT_CODE ON)
-endif()
+# Generate position independent code
+set_target_properties(igl_common PROPERTIES INTERFACE_POSITION_INDEPENDENT_CODE ON)
 
 # Eigen
 if(TARGET Eigen3::Eigen)