Patch fixes build on hurd-i386, kfreebsd-i386 and kfreebsd-amd64
atchitectures.

--- a/configure
+++ b/configure
@@ -10773,7 +10773,7 @@
 fi
 
 	    ;;
-	Linux*)
+	Linux*|GNU*)
 	    SHLIB_CFLAGS="-fPIC"
 	    SHLIB_LD_LIBS='${LIBS}'
 	    SHLIB_SUFFIX=".so"
--- a/tclconfig/tcl.m4
+++ b/tclconfig/tcl.m4
@@ -1574,7 +1574,7 @@
 	        ])
 	    ])
 	    ;;
-	Linux*)
+	Linux*|GNU*)
 	    SHLIB_CFLAGS="-fPIC"
 	    SHLIB_LD_LIBS='${LIBS}'
 	    SHLIB_SUFFIX=".so"