define HAVE_GAS_ALIGNED_COMM

HAVE_GAS_ALIGNED_COMM is referenced in an initializer in cygming.opt,
but it's not guaranteed to be defined by configure, so define it to
zero in a cygming-specific header if it's not defined.

for  gcc/ChangeLog

	* cygming.h (HAVE_GAS_ALIGNED_COMM): Fallback-define.

From-SVN: r265129

gcc/ChangeLog

+2018-10-12  Alexandre Oliva <oliva@adacore.com>
+
+	* cygming.h (HAVE_GAS_ALIGNED_COMM): Fallback-define.
+
 2018-10-12  Peter Bergner  <bergner@linux.ibm.com>
 
 	PR rtl-optimization/87600

gcc/config/i386/cygming.h

@@ -488,3 +488,7 @@ do {						\
 
 /* Static stack checking is supported by means of probes.  */
 #define STACK_CHECK_STATIC_BUILTIN 1
+
+#ifndef HAVE_GAS_ALIGNED_COMM
+# define HAVE_GAS_ALIGNED_COMM 0
+#endif