fix: unescaped LDVERSION in Android pkgconfig

This used to happen as LDVERSION was used in BLDLIBRARY declaration,
which was eventually used for LIBPYTHON. LDVERSION was thus changed to
be expanded at Makefile generation time. Furthermore, there were two
places where LDVERSION was been assigned. In order to make things
simpler, it is only defined and assigned once now. LDVERSION was used in
between the two assignments with different values, but was used as
'$(LDVERSION)', which means it was substituted to the later value
assigned in Makefiles at build time. So this should ideally have no
impact on the end user or the build process

Author: thunder-coding