Fix FIND_PROGRAM invocation for guile

CMakeLists.txt

@@ -261,11 +261,12 @@ IF (GUILE2_FOUND) # found guile-2.0
   SET(GUILE_INCLUDE_DIRS ${GUILE2_INCLUDE_DIRS})
   SET(GUILE_LDFLAGS ${GUILE2_LDFLAGS})
 
-  FIND_PROGRAM (GUILD_EXECUTABLE guild2.0 guild)
+  FIND_PROGRAM (GUILD_EXECUTABLE NAMES guild2.0 guild)
   IF (NOT GUILD_EXECUTABLE)
     MESSAGE (SEND_ERROR "The guild executable was not found, but is required. Please set GUILD_EXECUTABLE.")
   ENDIF (NOT GUILD_EXECUTABLE)
   MESSAGE(STATUS "Using guile-2.0.x")
+  FIND_PROGRAM (GUILE_EXECUTABLE NAMES guile2.0 guile)
 ELSE()
   # look for guile 1.8
   GNC_PKG_CHECK_MODULES (GUILE1 guile-1.8>=1.8.8 QUIET)
@@ -278,9 +279,9 @@ ELSE()
   SET(GUILE_INCLUDE_DIRS ${GUILE1_INCLUDE_DIRS})
   SET(GUILE_LDFLAGS ${GUILE1_LDFLAGS})
   MESSAGE(STATUS "Using guile-1.8.x")
+  FIND_PROGRAM (GUILE_EXECUTABLE NAMES guile1.8 guile)
 ENDIF()
 
-FIND_PROGRAM (GUILE_EXECUTABLE guile2.0 guile)
 IF (NOT GUILE_EXECUTABLE)
   MESSAGE (SEND_ERROR "The guile executable was not found, but is required. Please set GUILE_EXECUTABLE.")
 ENDIF (NOT GUILE_EXECUTABLE)