#2 flasm: fix build on gcc-10 (-fno-common)

[Sergei Trofimovich]

gcc-10 changed the default from -fcommon to fno-common:
https://gcc.gnu.org/PR85678

As a result build fails as:

ld: unflasm.o:/build/source/unflasm.c:32: multiple definition of
  `swfVersion'; flasm.o:/build/source/flasm.c:36: first defined here

The change makes 'swfVersion' a local variable to flasm and unflasm binaries.