Revert "libqt5core5.symbols: Merge duplicate symbols into single entries."

This reverts commit 2a200681ddc36834c2fa28bdf7a61f2222546a9c.

It's easier to just push pkgkde-tool's symbolshelper's changes if
symbols weren't modified.
Update symbols files.
Let qtbase build on MIPS.
Fix MIPS' FTBFS.
Release to experimental.