gh-100176: Mac/build-installer: Remove redundant compat code for Python 3.5 and older

[hugovk]

Python 3.5 has been EOL since 2020-09-13 and 2.7 since 2020-01-01, so we can remove these old compatibility checks.

https://devguide.python.org/versions/

• Issue: Meta issue: clean up redundant compat code #100176

[AlexWaygood]

Might as well modernise this 12-year-old code while we're here, since we're touching these lines anyway?

Suggested change

	fp = open(os.path.join(buildDir, 'Makefile'), 'r')
	for ln in fp:
	if ln.startswith('VERSION='):
	VERSION=ln.split()[1]
	if ln.startswith('ABIFLAGS='):
	ABIFLAGS=ln.split()
	ABIFLAGS=ABIFLAGS[1] if len(ABIFLAGS) > 1 else ''
	if ln.startswith('LDVERSION='):
	LDVERSION=ln.split()[1]
	fp.close()
	with open(os.path.join(buildDir, 'Makefile'), 'r') as fp:
	for ln in fp:
	if ln.startswith('VERSION='):
	VERSION=ln.split()[1]
	if ln.startswith('ABIFLAGS='):
	ABIFLAGS=ln.split()
	ABIFLAGS=ABIFLAGS[1] if len(ABIFLAGS) > 1 else ''
	if ln.startswith('LDVERSION='):
	LDVERSION=ln.split()[1]

(This might actually result in a smaller PR diff as well, as a bonus.)

[ned-deily]

Thanks for your efforts but I would prefer to leave build-installer.py untouched for now. I will be making much more substantial changes to it later in the current release cycle and for now it's easier to keep it in sync with other active versions.

[hugovk]

Sure! Let's close this.