Log Message:
spidermonkey52: Do not build with debug symbols and strip

configure forced to pass `-g' to CFLAGS and did not strip resulting binaries and
libraries. Pass `--disable-debug-symbols' and `--enable-strip' to respectively
address that.
Fix PR pkg/54228 reported by matt farnsworth.

While here, avoid to pass `-Wl,-z,wxneeded' to LDFLAGS on NetBSD.