redoconf: a stub rc_include() now sources ./redoconf.rc automatically.

This lets us remove the awkward ". ./redoconf.rc" line from zillions
of .od scripts, without paying the price of *always* including that
whole file every time default.do.sh is used.

docs/cookbook/c/all.rc.od

@@ -1,4 +1,3 @@
-. ./redoconf.rc
 rc_include \
 	rc/CC.required.rc \
 	rc/CXX.rc \

docs/cookbook/c/flagtest.o.od

@@ -1,7 +1,6 @@
 # Demonstrate how to compile .o files using nonstandard
 # compiler flags.  You could also do this for a whole
 # directory using default.o.od.
-. ./redoconf.rc
 rc_include all.rc
 
 src="$S/${1%.o}.c"

docs/cookbook/c/hello world.list.od

@@ -1,6 +1,5 @@
 # This script is run from the output dir.
 # The source dir is at $S.
-. ./redoconf.rc
 rc_include all.rc
 redo-ifchange "$S/sources"
 

docs/cookbook/c/rc/clock_gettime.rc.od

@@ -1,4 +1,3 @@
-. ./redoconf.rc
 rc_include rc/CC.rc rc/rt.autolib.rc rc/posix.rc
 
 prog="

docs/cookbook/c/rc/extra.rc.od

@@ -1,4 +1,3 @@
-. ./redoconf.rc
 rc_include
 
 rc_appendln CPPFLAGS "-DEXTRA_RC_INCLUDED=1"

docs/cookbook/c/rc/posix.rc.od

@@ -1,4 +1,3 @@
-. ./redoconf.rc
 rc_include rc/CC.rc
 
 prog='

docs/cookbook/c/rc/printf_lld.rc.od

@@ -1,4 +1,3 @@
-. ./redoconf.rc
 rc_include rc/CC.rc rc/windows.h.rc rc/Wall.rc
 
 appendln CPPFLAGS "-Werror"  # abort if any warnings