configury update & bump VERSION to 0.9.28rc

configure:
- option --targetos=... for cross build
- cleanup

win32/build-tcc.bat:
- option -b <bindir>
- make 'libtcc1.a' and cross-prefix-libtcc1.a
  (same convention as with makefile)

Makefile:
- streamline tcov-tests, help, etc.

workflow/build.xml: simplify
- using "windows-2019" runner (instead of windows-latest)
  because its msys seems more complete and has no problems
  with the 96_nodata_wanted.test either.

Changelog,TODO,USES,tcc-doc.texi: update

tests/pp/Makefile

@@ -10,7 +10,7 @@ VPATH = $(SRC)
 files = $(patsubst %.$1,%.test,$(notdir $(wildcard $(SRC)/*.$1)))
 TESTS = $(call files,c) $(call files,S)
 
-all test testspp.all testcpp.all: $(sort $(TESTS))
+all test testspp.all: $(sort $(TESTS))
 
 DIFF_OPTS = -Nu -b
 
@@ -29,7 +29,7 @@ FILTER = 2>&1 | sed 's,$(SRC)/,,g'
 	    diff $(DIFF_OPTS) $(SRC)/$*.expect $*.output \
 	    && rm -f $*.output
 
-testspp.% testcpp.%: %.test ;
+testspp.%: %.test ;
 
 # automatically generate .expect files with gcc:
 %.expect: # %.c

tests/tests2/Makefile

@@ -124,7 +124,7 @@ endif
 # Filter source directory in warnings/errors (out-of-tree builds)
 FILTER = 2>&1 | sed -e 's,$(SRC)/,,g'
 
-all test tests2.all testc2.all: $(filter-out $(SKIP),$(TESTS))
+all test tests2.all: $(filter-out $(SKIP),$(TESTS))
 	@$(MAKE) clean --no-print-directory -s
 
 %.test: %.c %.expect
@@ -138,15 +138,15 @@ T3 = $(FILTER) >$*.output 2>&1 || true \
      && rm -f $*.output $(filter $*.expect,$(GEN-ALWAYS))
 
 # run single test and update .expect file, e.g. "make tests2.37+"
-tests2.%+ testc2.%+:
+tests2.%+:
 	@$(MAKE) $(call F2,$(call F1,$*)) --no-print-directory
 
 # just run tcc to see the output, e.g. "make tests2.37-"
-tests2.%- testc2.%-:
+tests2.%-:
 	@$(MAKE) $(call F1,$*) T3= --no-print-directory
 
 # run single test, e.g. "make tests2.37"
-tests2.% testc2.%:
+tests2.%:
 	@$(MAKE) $(call F1,$*) --no-print-directory
 
 F1 = $(or $(filter $1_%,$(TESTS)),$1_???.test)