Makefile, src/Makefile: try fixing parallel builds & installs

- try going earlier for MAKE_VERSION with .WAIT in SUBDIR for ubuntu-20.04
- installs maybe needed a slash after DESTDIR for install_dirs targets
- don't also include realall in target list for lib${LIB}.dylib

Makefile

@@ -257,7 +257,7 @@ SUBDIR =	src
 #
 .if !defined(MAKE_VERSION) || \
 	(defined(unix) && ${unix} == "We run Unix"&& ${MAKE} != "bsdmake") || \
-	(${MAKE_VERSION} >= 20240212 && ${MAKE} != "bsdmake") || \
+	(${MAKE_VERSION} >= 20181221 && ${MAKE} != "bsdmake") || \
 	(defined(.FreeBSD) && ${.FreeBSD} == "true")
 SUBDIR +=	.WAIT
 SUBDIR_PARALLEL = 1 # defined, for FreeBSD....
@@ -384,7 +384,7 @@ _bmake_install_dirs: .PHONY
 # jobs during install from running ahead of the install directories being
 # made....
 #
-${bmake_install_dirs:S|^|${DESTDIR}|}: _bmake_install_dirs
+${bmake_install_dirs:S|^|${DESTDIR}/|}: _bmake_install_dirs
 
 # include the "standard" mk-file for building in sub-directories
 #

src/Makefile

@@ -225,10 +225,8 @@ lib${LIB}.dylib: lib${LIB}.so.${SHLIB_FULLVERSION}
 #	@echo fixing up shared library name for macos: ${.TARGET}
 #	ln -sf lib${LIB}.so.${SHLIB_FULLVERSION} ${.TARGET}
 
-# xxx why does this have realall too?
-realall all: lib${LIB}.dylib
+all: lib${LIB}.dylib
 
-# xxx this 
 afterinstall: ${DESTDIR}${LIBDIR}/lib${LIB}.dylib
 
 ${DESTDIR}${LIBDIR}/lib${LIB}.dylib: