[texinfo] @7.0: needs c-11 syntax (#34261)

gnulib/lib/malloca.c uses single value `static_assert()` only available in c-11
syntax. `gcc` seems to be fine, but `icc` needs extra flag.

Co-authored-by: Stephen Sachs <stesachs@amazon.com>

var/spack/repos/builtin/packages/texinfo/package.py

@@ -3,7 +3,6 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
-
 import re
 
 from spack.package import *
@@ -55,6 +54,13 @@ class Texinfo(AutotoolsPackage, GNUMirrorPackage):
 
     patch("nvhpc.patch", when="%nvhpc")
 
+    @property
+    def build_targets(self):
+        targets = []
+        if self.spec.satisfies("@7.0:"):
+            targets.append("CFLAGS={}".format(self.compiler.c11_flag))
+        return targets
+
     @classmethod
     def determine_version(cls, exe):
         output = Executable(exe)("--version", output=str, error=str)