BLD: suppress useless warnings
BLD: suppress useless warnings

Author: Jeff Reback <jeff@reback.net>

Closes #12589 from jreback/warnings and squashes the following commits:

0156618 [Jeff Reback] BLD: suppress useless warnings

Winand/pandas,pratapvardhan/pandas,amolkahat/pandas,winklerand/pandas,jmmease/pandas,linebp/pandas,pratapvardhan/pandas,jorisvandenbossche/pandas,GuessWhoSamFoo/pandas,harisbal/pandas,toobaz/pandas,MJuddBooth/pandas,cbertinato/pandas,cbertinato/pandas,MJuddBooth/pandas,gfyoung/pandas,linebp/pandas,jmmease/pandas,amolkahat/pandas,toobaz/pandas,rs2/pandas,pandas-dev/pandas,rs2/pandas,dsm054/pandas,toobaz/pandas,cython-testbed/pandas,gfyoung/pandas,GuessWhoSamFoo/pandas,MJuddBooth/pandas,jmmease/pandas,linebp/pandas,amolkahat/pandas,dsm054/pandas,Winand/pandas,kdebrab/pandas,jreback/pandas,winklerand/pandas,jreback/pandas,datapythonista/pandas,GuessWhoSamFoo/pandas,cbertinato/pandas,MJuddBooth/pandas,rs2/pandas,dsm054/pandas,dsm054/pandas,DGrady/pandas,datapythonista/pandas,pandas-dev/pandas,Winand/pandas,winklerand/pandas,louispotok/pandas,GuessWhoSamFoo/pandas,toobaz/pandas,harisbal/pandas,linebp/pandas,Winand/pandas,nmartensen/pandas,zfrenchee/pandas,cbertinato/pandas,GuessWhoSamFoo/pandas,TomAugspurger/pandas,jorisvandenbossche/pandas,Winand/pandas,harisbal/pandas,gfyoung/pandas,MJuddBooth/pandas,datapythonista/pandas,zfrenchee/pandas,nmartensen/pandas,louispotok/pandas,cython-testbed/pandas,jmmease/pandas,jorisvandenbossche/pandas,jreback/pandas,louispotok/pandas,rs2/pandas,pandas-dev/pandas,kdebrab/pandas,nmartensen/pandas,Winand/pandas,kdebrab/pandas,louispotok/pandas,gfyoung/pandas,DGrady/pandas,jmmease/pandas,linebp/pandas,DGrady/pandas,cython-testbed/pandas,jreback/pandas,pratapvardhan/pandas,toobaz/pandas,dsm054/pandas,winklerand/pandas,pratapvardhan/pandas,pratapvardhan/pandas,amolkahat/pandas,DGrady/pandas,nmartensen/pandas,amolkahat/pandas,gfyoung/pandas,harisbal/pandas,datapythonista/pandas,TomAugspurger/pandas,nmartensen/pandas,cbertinato/pandas,DGrady/pandas,jmmease/pandas,kdebrab/pandas,zfrenchee/pandas,TomAugspurger/pandas,kdebrab/pandas,linebp/pandas,cython-testbed/pandas,jorisvandenbossche/pandas,winklerand/pandas,TomAugspurger/pandas,cython-testbed/pandas,DGrady/pandas,zfrenchee/pandas,zfrenchee/pandas,harisbal/pandas,pandas-dev/pandas,jreback/pandas,louispotok/pandas,winklerand/pandas,nmartensen/pandas