[PR] Fdata: Escape whitespaces in symbol names

Summary:
This patch is part of preparation for golang support. The golang symbols
might have spaces in the name (for example "type..eq.[10]interface {}").
Since fdata uses spaces as a field separator such names brakes the fdata
format, so we need to escape whitespaces and backslashes in symbol names
using the backslash character.

Vladislav Khmelevsky,
Advanced Software Technology Lab, Huawei

(cherry picked from FBD29999491)