abuild: use BOOTSTRAP to determine if build-base is needed

Just checking the build, host and target triplet is not enough
due to various different combinations used in the early bootstrap.
So use detect specifical bootstrap setting.

abuild.in

@@ -1855,19 +1855,19 @@ calcdeps() {
 
 # build and install dependencies
 builddeps() {
-	local pkg= i= missing=
+	local pkg= i= missing= BUILD_BASE=
 	local installed_hostdeps= installed_builddeps=
 	[ -n "$nodeps" ] && return 0
 
 	msg "Analyzing dependencies..."
-	local BUILD_BASE=""
-	if cross_creating; then
-		options_has toolchain || BUILD_BASE="build-base-$CTARGET_ARCH"
-	elif cross_compiling; then
-		BUILD_BASE="build-base-$CTARGET_ARCH"
-	else
-		BUILD_BASE="build-base"
-	fi
+	case "$BOOTSTRAP" in
+	no*)	BUILD_BASE="";;
+	*)	if cross_creating || cross_compiling; then
+			BUILD_BASE="build-base-$CTARGET_ARCH"
+		else
+			BUILD_BASE="build-base"
+		fi
+	esac
 	calcdeps "$BUILD_BASE"
 
 	installed_builddeps=$($APK info --installed $builddeps)