xbps-src: new layout in masterdir to use a common directory from host.

XBPS_CACHEDIR has been replaced by XBPS_HOSTDIR in configuration file,
and this expects the following structure:

/host
  |_ /build (previously /pkg-builddir)
  |_ /binpkgs (previously /pkg-binpkgs)
  |_ /repocache (previously /cachedir)
  |_ /sources (previously /pkg-srcdistdir)

Thanks to str1ngs for the great idea!

xbps-src/xbps-src.sh.in

@@ -80,7 +80,7 @@ Targets:
 
  extract [pkgname]
 	Extract package source distribution file(s) into the build directory.
-	By default set to <masterdir>/pkg-builddir.
+	By default set to <masterdir>/host/build.
 
  fetch [pkgname]
 	Download package source distribution file(s).
@@ -102,7 +102,7 @@ Targets:
  make-repoidx
 	Build a package index for the local repository associated with
 	the master directory <masterdir>. By default set to
-	<masterdir>/pkg-binpkgs. To specify another repo, use -p <dir>.
+	<masterdir>/host/binpkgs. To specify another repo, use -p <dir>.
 
  remove [pkgname]
 	Remove package completely from <destdir> and <masterdir>.
@@ -131,19 +131,19 @@ Options:
  -c     Path to global configuration file:
         if not specified @@XBPS_INSTALL_ETCDIR@@/xbps-src.conf is used.
  -D     Only install <pkgname> to package's destination directory set
-        to <masterdir>/pkg-destdir/<pkgname>-<version>.
+        to <masterdir>/host/destdir/<pkgname>-<version>.
  -h	Usage output.
  -K     Do not remove automatic package dependencies while building
         or installing a package with XBPS_PREFER_BINPKG_DEPS enabled.
  -m     Master directory, overwritting the value set in the configuration
         file xbps-src.conf.
  -p     Local packages repository, overwritting default path at
-        <masterdir>/pkg-binpkgs.
+        <masterdir>/host/binpkgs.
  -S     Overrides and disables XBPS_PREFER_BINPKG_DEPS even if it was
         set in the configuration file xbps-src.conf.
         it was set in the configuration file.
  -s     Source distribution files directory, overwritting default path at
-        <masterdir>/pkg-srcdistdir.
+        <masterdir>/host/sources.
 
 _EOF
 }