Make the %py3_dist macro compatible with Python RPM generators

Fix the %py_build macro to respect the global definition of %__python

%python_provide: Obsolete and provide python36- from python3-
%python_provide: Provide python3- from python36-

Converting specfile from F28 to RHEL7
Move the macros to the standard RHEL7 macro location at /etc/rpm/,
Import the macros.python{,2} files from the python-devel package where they
devel
Import the macros.pybytecompile from Fedora rawhide / RHEL8

Backport %python3_platform macro.

Add %pypi_source macro.

Fix the %py_dist_name macro to not convert dots (".") into dashes, so that

make LDFLAGS propagated whenever CFLAGS are

Rebuilt for https://fedoraproject.org/wiki/Fedora_28_Mass_Rebuild

Add %python_enable_dependency_generator

Remove platform-python macros (https://fedoraproject.org/wiki/Changes/Platform_Python_Stack)

Use -Es/-I to invoke macro scriptlets (#1506355)

Add platform-python macros (https://fedoraproject.org/wiki/Changes/Platform_Python_Stack)

Rebuilt for https://fedoraproject.org/wiki/Fedora_27_Mass_Rebuild

Revert "Switch %__python3 to /usr/libexec/system-python"

Switch %__python3 to /usr/libexec/system-python