math/fftw3: Update to 3.3.11

Clean up whitespace and order Makefile. Simplify some logic including
removing -malign-double for i386, which could break programs linked to
the quad library. Nothing uses quad, so it's moot keeping complicated
logic for a Tier-2 platform.

All supported versions of FreeBSD have <bsd.cpu.mk> with altivec support
in MACHINE_CPU. Remove obsolete workaround.

Add a few maintainer helper targets to make updates a bit easier.
These automatically update SHLIB_VER_MIN variable in the Makefile and
regenerate FFTW3LibraryDepends.cmake.in. After just bumping PORTVERSION
and removing any existing PORTREVISION line, simply running:
make -C ${PORTSDIR}/math/fftw -DMAINTAINER_MODE maintainer-update
will take care of all of the pre-test tasks.

MFH: 2026Q4
(cherry picked from commit 2c75ab24ce68f5185a6ebcb2eda33ad0575ccaf8)