Move _heap.h to the compiler include dir.

Create heap.inc and use that from the assembler code.
Rename heap related _h... variables to _heap...
Add _heapmaxavail and _heapmemavail functions.


git-svn-id: svn://svn.cc65.org/cc65/trunk@1912 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/common/Makefile

@@ -54,6 +54,8 @@ S_OBJS = 	_fdesc.o 	\
 		_fopen.o	\
 	 	_heap.o	 	\
        	       	_heapadd.o 	\
+                _heapmaxavail.o \
+                _heapmemavail.o \
 	 	_oserror.o	\
 		_printf.o	\
 		_swap.o		\