internal/rosa/package: migrate many libraries

This also adds more string helpers.

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

internal/rosa/package/libucontext.az

@@ -0,0 +1,28 @@
+package libucontext {
+	description = "ucontext implementation featuring glibc-compatible ABI";
+	website = "https://github.com/kaniini/libucontext";
+	anitya = 17085;
+
+	version* = "1.5.1";
+	source = remoteGitHub {
+		suffix = "kaniini/libucontext";
+		tag = "libucontext-"+version;
+		checksum = "mUgeyJknjMxT-5fORzz-rqhZfP3Y7EZGBhOwvhuX7MsF4Pk9wkuwtrLf5IML-jWu";
+	};
+
+	// uses source tree as scratch space
+	writable = true;
+	chmod = true;
+	enterSource = true;
+
+	exec = make {
+		omitDefaults = true;
+		skipConfigure = true;
+		inPlace = true;
+
+		make = [
+			"ARCH=" + linuxArch,
+		];
+		install = "make prefix=/system DESTDIR=/work install";
+	};
+}