libopen62541: preserve symlinks on install

[BrelJordan]

fix libopen62541 Makefile to copy lib without following symlinks.

[GeorgeSapkin]

From this description alone it's not clear how exactly this saves space.

And you have to adjust the commit title to follow the 50/75 rule.

[BrelJordan]

I updated the commit message to comply with the 50/75 rule and added a clearer description of what the changes do.

$(INSTALL_BIN) follows symlinks, causing the .so to be copied multiple times.
Use $(CP) instead to preserve symlinks and cut package size by ~2/3.
OpenWrt libraries don’t need to be executable, so $(INSTALL_BIN) isn’t required.

[BKPepe]

$(INSTALL_BIN) follows symlinks, causing the .so to be copied multiple times.
Use $(CP) instead to preserve symlinks and cut package size by ~2/3.

Ideally, it should be like this: #23512 or even like this openwrt/openwrt@38b22b1

I think, we need one more round of #9233 , because it looks like a few packages again are doing it:-)

But fine by me. Merging!