imake: Patch to work with superenv

Closes #16420.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Library/Formula/imake.rb

@@ -13,6 +13,12 @@ class Imake < Formula
   depends_on 'pkg-config' => :build
   depends_on :x11
 
+  def patches
+    # Remove cpp whitespace check and add "-" to pass the cpp -undef test.
+    # These are needed to support superenv (which uses clang)
+    DATA
+  end
+
   def install
     ENV.deparallelize
     system './configure', "--prefix=#{prefix}", '--disable-dependency-tracking'
@@ -24,3 +30,44 @@ def install
     end
   end
 end
+
+__END__
+diff --git a/configure b/configure
+index d4c46f0..4a31a8a 100755
+--- a/configure
++++ b/configure
+@@ -10581,7 +10581,7 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ /* end confdefs.h.  */
+ Does cpp redefine unix ?
+ _ACEOF
+-if test `${RAWCPP} < conftest.$ac_ext | grep -c 'unix'` -eq 1 ; then
++if test `${RAWCPP} - < conftest.$ac_ext | grep -c 'unix'` -eq 1 ; then
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+ $as_echo "no" >&6; }
+ else
+@@ -10600,27 +10600,6 @@ $as_echo "yes, with -ansi" >&6; }
+ fi
+ rm -f conftest.$ac_ext
+
+-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if $RAWCPP requires -traditional" >&5
+-$as_echo_n "checking if $RAWCPP requires -traditional... " >&6; }
+-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+-/* end confdefs.h.  */
+-Does cpp preserve   "whitespace"?
+-_ACEOF
+-if test `${RAWCPP} < conftest.$ac_ext | grep -c 'preserve   \"'` -eq 1 ; then
+-	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+-$as_echo "no" >&6; }
+-else
+-	if test `${RAWCPP} -traditional < conftest.$ac_ext | grep -c 'preserve   \"'` -eq 1 ; then
+-		RAWCPPFLAGS="${RAWCPPFLAGS} -traditional"
+-		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+-$as_echo "yes" >&6; }
+-	else
+-		as_fn_error $? "${RAWCPP} does not preserve whitespace with or without -traditional.  I don't know what to do." "$LINENO" 5
+-	fi
+-fi
+-rm -f conftest.$ac_ext
+-
+-
+ CPP_PROGRAM=${RAWCPP}