[smuxi/stable] configure.ac: use 4.5 by default and downgrade to 4.0 or 3.5 if necessary

[Mirco M. M. Bauer <mmmbauer src gnome org>]

commit 5b8c65c1272cbf0c0b5cb7b4b11ef636d9c1cbe8
Author: Mirco Bauer <meebey meebey net>
Date:   Mon Jan 18 19:15:24 2016 +0100

    configure.ac: use 4.5 by default and downgrade to 4.0 or 3.5 if necessary

 configure.ac |   20 +++++++++++++++++---
 1 files changed, 17 insertions(+), 3 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index edf381f..ad5c077 100644
--- a/configure.ac
+++ b/configure.ac
@@ -199,9 +199,9 @@ fi
 AC_SUBST(CSC_FLAGS)
 
 MCS_BASENAME=$(basename $MCS)
-CLI_RUNTIME=
+CLI_RUNTIME=4.5
 if test "$MCS_BASENAME" = "gmcs"; then
-       CLI_RUNTIME=2.0
+       CLI_RUNTIME=3.5
 fi
 if test "$MCS_BASENAME" = "dmcs"; then
        CLI_RUNTIME=4.0
@@ -209,7 +209,21 @@ fi
 if test "$MCS_BASENAME" = "mcs"; then
        CLI_RUNTIME=4.5
 fi
-if test "$CLI_RUNTIME" = "2.0"; then
+if test "$CLI_RUNTIME" = "4.5"; then
+       if test ! -e "$($PKG_CONFIG --variable=libdir mono)/mono/4.5/mscorlib.dll" -a \
+                       ! -e "$($PKG_CONFIG --variable=prefix mono)/lib/mono/4.5/mscorlib.dll"; then
+               # Mono without 4.5 support -> downgrade to 4.0
+               CLI_RUNTIME=4.0
+       fi
+fi
+if test "$CLI_RUNTIME" = "4.0"; then
+       if test ! -e "$($PKG_CONFIG --variable=libdir mono)/mono/4.0/mscorlib.dll" -a \
+                   ! -e "$($PKG_CONFIG --variable=prefix mono)/lib/mono/4.0/mscorlib.dll"; then
+               # Mono without 4.0 support -> downgrade to 3.5
+               CLI_RUNTIME=3.5
+       fi
+fi
+if test "$CLI_RUNTIME" = "3.5"; then
        XBUILD_FLAGS="/toolsversion:3.5 /p:TargetFrameworkVersion=v3.5 /property:DefineConstants=MONO_3_5"
 fi
 if test "$CLI_RUNTIME" = "4.0"; then