Add SEPLOG make variable, and add it to LOGFILES value

tests/Makefile

@@ -2541,7 +2541,12 @@ endif
 ifndef LOG
 export LOG:=$(TEST_OUTPUTDIR)/log
 endif
-LOGFILES=$(TEST_OUTPUTDIR)/log $(TEST_OUTPUTDIR)/longlog $(TEST_OUTPUTDIR)/faillist
+ifndef SEPLOG
+ifdef MAKEINC_SEPARATE
+export SEPLOG:=$(TEST_OUTPUTDIR)/seplog
+endif
+endif
+LOGFILES=$(LOG) $(LONGLOG) $(FAILLIST) $(SEPLOG)
 LOGEXT=.testlog .tbslog .tbflog .webtbslog .webtbflog
 TESTUNITDIRS=system dos crt objects strings sysutils math sharemem strutils matrix lineinfo ucomplex fpwidestring cpu fmtbcd windows classes character dateutil fpcunit softfpu variants sortbase sortalgs linux unixutil types nullable contnrs convutils
 TESTDIRECTDIRS=

tests/Makefile.fpc

@@ -154,14 +154,21 @@ ifndef LOG
 export LOG:=$(TEST_OUTPUTDIR)/log
 endif
 
+ifndef SEPLOG
+ifdef MAKEINC_SEPARATE
+export SEPLOG:=$(TEST_OUTPUTDIR)/seplog
+endif
+endif
+
 # locations of all logfiles
-LOGFILES=$(TEST_OUTPUTDIR)/log $(TEST_OUTPUTDIR)/longlog $(TEST_OUTPUTDIR)/faillist
+LOGFILES=$(LOG) $(LONGLOG) $(FAILLIST) $(SEPLOG)
 LOGEXT=.testlog .tbslog .tbflog .webtbslog .webtbflog
 
 # Subdirs available in the test subdir
 TESTUNITDIRS=system dos crt objects strings sysutils math sharemem strutils matrix lineinfo ucomplex fpwidestring cpu fmtbcd windows classes character dateutil fpcunit softfpu variants sortbase sortalgs linux unixutil types nullable contnrs convutils
 TESTDIRECTDIRS=
 TESTSUBDIRS=cg cg/variants cg/cdecl cpu8/avr cpu16 cpu16/i8086 library opt wasm $(addprefix units/,$(TESTUNITDIRS))
+
 TESTPACKAGESDIRS=win-base webtbs hash fcl-registry fcl-process zlib fcl-db fcl-xml cocoaint bzip2 fcl-net
 TESTPACKAGESUBDIRS=$(addprefix packages/,$(TESTPACKAGESDIRS))
 TESTPACKAGESDIRECTDIRS=rtl-objpas rtl-generics hash regexpr fcl-registry fcl-passrc fcl-json fcl-image pastojs fcl-process