Implements init_dataframe as multiple codegen functions

[kozlov-alexey]

Motivation: init_dataframe was implemented via Numba intrinsic taking *args,
which seems to generate redundant extractvalue/insertvalue LLVM
instructions, producing quadratic IR when number of DF columns grows and affecting
total compilation time of function that create large DFs. This PR
replaces singe init_dataframe with multiple functions basing on number of columns
in a DF which are generated at compile time, thus avoiding use of *args.

n_columns		8	16	32	64	128	256	512
LLVM IR size, Mb	on master	0.287622	0.55394	1.262865	3.383549	10.44003	35.79943	131.384
LLVM IR size, Mb	With PR #936	0.143275	0.209119	0.341938	0.608992	1.143528	2.220672	4.406426
ratio without/with		2.007482	2.648924	3.693257	5.555986	9.12967	16.12099	29.81645
compilation time, s	on master	0.521313	0.366884	0.67621	1.39326	4.603106	17.54948	126.7943
compilation time, s	With PR #936	0.683099	0.413965	0.450348	0.715598	1.454044	3.210638	6.943996
ratio without/with		0.763159	0.886268	1.501529	1.946987	3.165726	5.466041	18.25956

[pep8speaks]

Hello @kozlov-alexey! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2020-11-13 15:02:36 UTC

[kozlov-alexey]

Test failures of read_csv tests with:

Failed in nopython mode pipeline (step: nopython rewrites)
module 'sdc.hiframes.pd_dataframe_ext' has no attribute 'init_dataframe'

are expected because this PR requires changes from #918 which was rolled-back recently. So this will be blocked until #918 is returned.

[AlexanderKalistratov]

@kozlov-alexey @xaleryb win 3.6 build fails with svml error again:

test_series_apply_np (sdc.tests.test_series.TestSeries) ... LLVM ERROR: Symbol not found: __svml_log4_ha

[kozlov-alexey]

@kozlov-alexey @xaleryb win 3.6 build fails with svml error again:

test_series_apply_np (sdc.tests.test_series.TestSeries) ... LLVM ERROR: Symbol not found: __svml_log4_ha

I think something's wrong with the packages being used (see mkl and many others are installed from public channels, but not built). Can this be a reason?