Disable parallel GNU make for now

Unfortunately due to the complex dependency issues between
Makefile, Makefile.ship and custom/Makefile, parallel GNU make
is NOT recommended.  Sorry (tm Canada) :)

CHANGES

@@ -55,6 +55,13 @@ The following are the changes from calc version 2.14.0.0 to date:
     the precision of the internal constant pi/200.
     The optional 2nd argument is ignored by g2d(grad, ep) and d2g(deg, ep).
 
+    The clean and clobber makefile rules no longer list custom/Makefile
+    as a dependecy.
+
+    Unfortunately due to the complex dependency issues between
+    Makefile, Makefile.ship and custom/Makefile, parallel GNU make
+    is NOT recommended.  Sorry (tm Canada) :)
+
 
 The following are the changes from calc version 2.13.0.1 to 2.13.0.1:
 
@@ -1379,12 +1386,12 @@ The following are the changes from calc version 2.12.1.10 to 2.12.2:
     The custom/Makefile is now constructed from 3 parts: custom/Makefile.head,
     the host target section in Makefile, and the custom/Makefile.tail.
 
-    The top level Makefile and the custom/Makefile require a GNU Make
+    The top level Makefile and the custom/Makefile require a GNU make
     (such as gmake) or an equivalently advanced make.  On many targets,
     the default make is sufficient.  On FreeBSD for example, one must
     use gmake instead of make.
 
-    If your target system does not have GNU Make (or equivalent), then
+    If your target system does not have GNU make (or equivalent), then
     you should try using the Makefile.simple and custom/Makefile.simple
     files:
 

HOWTO.INSTALL

@@ -2,6 +2,14 @@
 IMPORTANT: Please see the section at the bottom of this file for
 	   some important information on Makefiles used in calc.
 
+###################################################################
+# IMPORTANT: DO NOT run GNU make in parallel mode!!!		  #
+###################################################################
+# Unfortunately due to the complex dependency issues between	  #
+# Makefile, Makefile.ship and custom/Makefile, parallel GNU make  #
+# is NOT recommended.  Sorry (tm Canada) :)			  #
+###################################################################
+
 Installing calc from the bzip2-ed tarball in 4 easy steps:
 
     (0)  If your platform supports i686 RPMs, you may want to go to:

Makefile

@@ -35,6 +35,12 @@
 # calculator by David I. Bell with help/mods from others
 # Makefile by Landon Curt Noll
 
+# Unfortunately due to the complex dependency issues between
+# Makefile, Makefile.ship and custom/Makefile, parallel GNU make
+# is NOT recommended.  Sorry.
+#
+.NOTPARALLEL:
+
 # Try uname -s if the target was not already set on the make command line
 #
 ifeq ($(target),)

Makefile.ship

@@ -59,6 +59,13 @@ SHELL= /bin/sh
 
 
 #if 0	/* start of skip for non-Gnu makefiles */
+
+# Unfortunately due to the complex dependency issues between
+# Makefile, Makefile.ship and custom/Makefile, parallel GNU make
+# is NOT recommended.  Sorry.
+#
+.NOTPARALLEL:
+
 ##############################################################################
 #-=-=-=-=-=-=-=-=- Identify the target machine, if possible -=-=-=-=-=-=-=-=-#
 ##############################################################################

custom/Makefile

@@ -145,6 +145,13 @@ CCBAN= -UUNBAN
 
 
 #if 0	/* start of skip for non-Gnu makefiles */
+
+# Unfortunately due to the complex dependency issues between
+# Makefile, Makefile.ship and custom/Makefile, parallel GNU make
+# is NOT recommended.  Sorry.
+#
+.NOTPARALLEL:
+
 ##############################################################################
 #-=-=-=-=-=-=-=-=- Identify the target machine, if possible -=-=-=-=-=-=-=-=-#
 ##############################################################################

custom/Makefile.head

@@ -145,6 +145,13 @@ CCBAN= -UUNBAN
 
 
 #if 0	/* start of skip for non-Gnu makefiles */
+
+# Unfortunately due to the complex dependency issues between
+# Makefile, Makefile.ship and custom/Makefile, parallel GNU make
+# is NOT recommended.  Sorry.
+#
+.NOTPARALLEL:
+
 ##############################################################################
 #-=-=-=-=-=-=-=-=- Identify the target machine, if possible -=-=-=-=-=-=-=-=-#
 ##############################################################################