CI: Clean up OSGeo4W workflow scripts (#2675)

* build_osgeo4w.sh: Delete outdated usage

* Escape backslashes

.github/workflows/build_osgeo4w.sh

@@ -19,4 +19,4 @@ export SRC=$(pwd)
 export UNITTEST=1
 
 # Build according to OSGeo4W recipe
-${SRC}/mswindows/osgeo4w/build_osgeo4W.sh
+${SRC}/mswindows/osgeo4w/build_osgeo4w.sh

mswindows/osgeo4w/build_osgeo4w.sh

@@ -1,7 +1,5 @@
 #!/bin/sh
 
-#
-# Usage: build_osgeo4w.sh
 #
 # The following environment variables are supposed to be passed to the build script
 # - SRC: the directory where the grass source code lives
@@ -12,12 +10,6 @@
 # and create bin.x86_64-w64-mingw32\grass$ver.bat (run this batch file to start
 # GRASS GIS) and dist.x86_64-w64-mingw32\etc\env.bat.
 #
-# -p	optionally install GRASS GIS to C:\OSGeo4W\opt\grass (run
-#	C:\OSGeo4W64\opt\grass\grass$ver.bat) and create an unzippable package
-#	grass$ver-x86_64-w64-mingw32-osgeo4w64-$date.zip
-#
-# path	specify a path to the source code
-#
 
 # stop on errors
 set -e
@@ -111,12 +103,12 @@ dist_esc="$src_esc\\\\$dist"
 
 set PATH=%PATH%;C:\\msys64\\mingw64\\bin;C:\\msys64\\usr\\bin
 
-if not exist %GISBASE%\etc\fontcap (
+if not exist %GISBASE%\\etc\\fontcap (
 	pushd .
 	%~d0
-	cd %GISBASE%\lib
+	cd %GISBASE%\\lib
 	set GISRC=dummy
-	%GISBASE%\bin\g.mkfontcap.exe
+	%GISBASE%\\bin\\g.mkfontcap.exe
 	popd
 )
 EOT
@@ -154,12 +146,12 @@ cp -a $(ldd $dist/lib/*.dll | awk '/mingw64/{print $3}' |
 
 set PATH=%OSGEO4W_ROOT%\\bin${msys_path};%PATH%;$bash_exe_path
 
-if not exist %GISBASE%\etc\fontcap (
+if not exist %GISBASE%\\etc\\fontcap (
 	pushd .
 	%~d0
-	cd %GISBASE%\lib
+	cd %GISBASE%\\lib
 	set GISRC=dummy
-	%GISBASE%\bin\g.mkfontcap.exe
+	%GISBASE%\\bin\\g.mkfontcap.exe
 	popd
 )
 EOT