msvc: unique names for pdb files, remove test job limit

.gitattributes

@@ -1,2 +1,3 @@
 *.v linguist-language=V text=auto eol=lf
 *.vv linguist-language=V text=auto eol=lf
+*.bat text=auto eol=crlf

cmd/tools/modules/testing/common.v

@@ -96,14 +96,6 @@ pub fn (mut ts TestSession) test() {
 		mtx: sync.new_mutex()
 	}
 	pool_of_test_runners.set_shared_context(ts)
-	$if msvc {
-		// NB: MSVC can not be launched in parallel, without giving it
-		// the option /FS because it uses a shared PDB file, which should
-		// be locked, but that makes writing slower...
-		// See: https://docs.microsoft.com/en-us/cpp/build/reference/fs-force-synchronous-pdb-writes?view=vs-2019
-		// Instead, just run tests on 1 core for now.
-		pool_of_test_runners.set_max_jobs(1)
-	}
 	pool_of_test_runners.work_on_pointers(remaining_files.pointers())
 	ts.benchmark.stop()
 	eprintln(term.h_divider('-'))

vlib/v/builder/msvc.v

@@ -200,6 +200,7 @@ pub fn (mut v Builder) cc_msvc() {
 		return
 	}
 	out_name_obj := os.real_path(v.out_name_c + '.obj')
+	out_name_pdb := os.real_path(v.out_name_c + '.pdb')
 	// Default arguments
 	// volatile:ms enables atomic volatile (gcc _Atomic)
 	// -w: no warnings
@@ -209,12 +210,17 @@ pub fn (mut v Builder) cc_msvc() {
 	if v.pref.is_prod {
 		a << '/O2'
 		a << '/MD'
-		a << '/Zi'
 		a << '/DNDEBUG'
 	} else {
-		a << '/Zi'
 		a << '/MDd'
 	}
+
+	if v.pref.is_debug {
+		// /Zi generates a .pdb
+		// /Fd sets the pdb file name (so its not just vc140 all the time)
+		a << ['/Zi', '/Fd"$out_name_pdb"']
+	}
+
 	if v.pref.is_shared {
 		if !v.pref.out_name.ends_with('.dll') {
 			v.pref.out_name += '.dll'
@@ -337,7 +343,7 @@ fn build_thirdparty_obj_file_with_msvc(path string, moduleflags []cflag.CFlag) {
 	// println('cfiles: $cfiles')
 	btarget := moduleflags.c_options_before_target_msvc()
 	atarget := moduleflags.c_options_after_target_msvc()
-	cmd := '"$msvc.full_cl_exe_path" /volatile:ms /Zi /DNDEBUG $include_string /c $btarget $cfiles $atarget /Fo"$obj_path"'
+	cmd := '"$msvc.full_cl_exe_path" /volatile:ms /DNDEBUG $include_string /c $btarget $cfiles $atarget /Fo"$obj_path"'
 	// NB: the quotes above ARE balanced.
 	println('thirdparty cmd line: $cmd')
 	res := os.exec(cmd) or {