ruby: fix uClibc-ng misdetection

package/ruby/patches/patch-configure

@@ -0,0 +1,16 @@
+--- ruby-2.4.0.orig/configure	2016-12-23 17:06:46.000000000 +0100
++++ ruby-2.4.0/configure	2017-01-30 03:08:52.351107663 +0100
+@@ -9412,6 +9412,13 @@ esac
+ 		ac_cv_func_isinf=yes
+ 		ac_cv_func_isnan=yes
+ 		 ;; #(
++  linux*) :
++    	LIBS="-lm $LIBS"
++		# finite(), isinf() and isnan() are macros on Linux.
++		ac_cv_func_finite=yes
++		ac_cv_func_isinf=yes
++		ac_cv_func_isnan=yes
++		 ;; #(
+   aix*) :
+     	LIBS="-lm $LIBS"
+ 		ac_cv_func_round=no