internal/rosa: respect preferred job count

This discontinues use of nproc, and also overrides detection behaviour in ninja.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/gnu.go

@@ -103,7 +103,7 @@ func (t Toolchain) newAutoconf() (pkg.Artifact, string) {
 		Flag: TExclusive,
 	}, &MakeHelper{
 		Check: []string{
-			`TESTSUITEFLAGS="-j$(nproc)"`,
+			"TESTSUITEFLAGS=" + jobsFlagE,
 			"check",
 		},
 	},
@@ -185,7 +185,7 @@ func (t Toolchain) newLibtool() (pkg.Artifact, string) {
 		pkg.TarGzip,
 	), nil, &MakeHelper{
 		Check: []string{
-			`TESTSUITEFLAGS="-j$(nproc)"`,
+			"TESTSUITEFLAGS=" + jobsFlagE,
 			"check",
 		},
 	},
@@ -732,7 +732,7 @@ func (t Toolchain) newTar() (pkg.Artifact, string) {
 			// very expensive
 			"TARTEST_SKIP_LARGE_FILES=1",
 
-			`TESTSUITEFLAGS="-j$(nproc)"`,
+			"TESTSUITEFLAGS=" + jobsFlagE,
 			"check",
 		},
 	},