Add pacman (alpm) parser support (#943)

Co-authored-by: Christopher Phillips <christopher.phillips@anchore.com>

internal/formats/common/spdxhelpers/source_info.go

@@ -9,6 +9,8 @@ import (
 func SourceInfo(p pkg.Package) string {
 	answer := ""
 	switch p.Type {
+	case pkg.AlpmPkg:
+		answer = "acquired package info from ALPM DB"
 	case pkg.RpmPkg:
 		answer = "acquired package info from RPM DB"
 	case pkg.ApkPkg:

internal/formats/common/spdxhelpers/source_info_test.go

@@ -142,6 +142,14 @@ func Test_SourceInfo(t *testing.T) {
 				"from dotnet project assets file",
 			},
 		},
+		{
+			input: pkg.Package{
+				Type: pkg.AlpmPkg,
+			},
+			expected: []string{
+				"from ALPM DB",
+			},
+		},
 	}
 	var pkgTypes []pkg.Type
 	for _, test := range tests {