Merge pull request #7265 from blueyed/rm-SPHINXPROJ

doc/{Makefile,make.bat}: remove unused SPHINXPROJ

doc/Makefile

@@ -5,7 +5,6 @@ PYTHON ?= python3
 # You can set these variables from the command line.
 SPHINXOPTS   =
 SPHINXBUILD  = $(PYTHON) ../sphinx/cmd/build.py
-SPHINXPROJ   = sphinx
 SOURCEDIR    = .
 BUILDDIR     = _build
 

doc/make.bat

@@ -7,7 +7,6 @@ if "%SPHINXBUILD%" == "" (
 )
 set SOURCEDIR=.
 set BUILDDIR=_build
-set SPHINXPROJ=sphinx-doc
 
 if "%1" == "" goto help