all: add #pkgconfig directive using the new vlib modules (#6673)

vlib/semver/semver.v

@@ -0,0 +1,82 @@
+// * Documentation: https://docs.npmjs.com/misc/semver
+module semver
+
+// * Structures.
+// Structure representing version in semver format.
+pub struct Version {
+pub:
+	major      int
+	minor      int
+	patch      int
+	prerelease string
+	metadata   string
+}
+
+// Enum representing type of version increment.
+pub enum Increment {
+	major
+	minor
+	patch
+}
+
+// * Constructor.
+// from returns Version structure parsed from input string.
+pub fn from(input string) ?Version {
+	if input.len == 0 {
+		return error('Empty input')
+	}
+	raw_version := parse(input)
+	version := raw_version.validate() or {
+		return error('Invalid version format')
+	}
+	return version
+}
+
+// build returns Version structure with given major, minor and patch versions.
+pub fn build(major int, minor int, patch int) Version {
+	// TODO Check if versions are greater than zero.
+	return Version{major, minor, patch, '', ''}
+}
+
+// * Transformation.
+// increment returns Version structure with incremented values.
+pub fn (ver Version) increment(typ Increment) Version {
+	return increment_version(ver, typ)
+}
+
+// * Comparison.
+pub fn (ver Version) satisfies(input string) bool {
+	return version_satisfies(ver, input)
+}
+
+pub fn (v1 Version) eq(v2 Version) bool {
+	return compare_eq(v1, v2)
+}
+
+pub fn (v1 Version) gt(v2 Version) bool {
+	return compare_gt(v1, v2)
+}
+
+pub fn (v1 Version) lt(v2 Version) bool {
+	return compare_lt(v1, v2)
+}
+
+pub fn (v1 Version) ge(v2 Version) bool {
+	return compare_ge(v1, v2)
+}
+
+pub fn (v1 Version) le(v2 Version) bool {
+	return compare_le(v1, v2)
+}
+
+// * Utilites.
+pub fn coerce(input string) ?Version {
+	ver := coerce_version(input) or {
+		return error('Invalid version: $input')
+	}
+	return ver
+}
+
+pub fn is_valid(input string) bool {
+	return is_version_valid(input)
+}