If the user doesn't mandate --prefix=, assume a value

This fixes build failures where the libjpeg/libtiff/libgif linking logic forces use of --prefix, which resolves to NONE - e.g. https://jenkins.mono-project.com/job/test-libgdiplus-mainline/22/label=ubuntu-1404-amd64/consoleFull
mono · Oct 12, 2016 · eaa874f · eaa874f
1 parent 1cbd58e
commit eaa874f
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/configure.ac b/configure.ac
@@ -196,6 +196,11 @@ fi
 AC_ARG_WITH(libexif,
 	[AC_HELP_STRING([--without-libexif], [disable EXIF support])])
 
+dnl If the user doesn't force a --prefix= then assume the OS default for resolcing libtiff etc
+case $prefix in
+NONE) prefix=$ac_default_prefix ;;
+esac
+
 dnl Test for libjpeg (this needs to be checked before libtiff, since libtiff depends on libjpeg)
 AC_ARG_WITH([libjpeg],
 	AS_HELP_STRING([--with-libjpeg=PREFIX],