geary: fix build on ppc*-musl and i686-musl

srcpkgs/geary/patches/libucontext.patch

@@ -0,0 +1,14 @@
+For whatever reason they don't use pkg-config for this.
+We will substitute this as needed from the template.
+
+--- meson.build
++++ meson.build
+@@ -138,7 +138,8 @@ if libunwind_dep.found()
+      dependencies: [
+        valac.find_library('libunwind', dirs: [vapi_dir, unwind_lib]),
+        cc.find_library('libunwind', dirs: unwind_lib),
+-       cc.find_library('libunwind-generic', dirs: unwind_lib)
++       cc.find_library('libunwind-generic', dirs: unwind_lib),
++       @UCONTEXT_LIB@
+      ],
+    )

srcpkgs/geary/template

@@ -18,3 +18,15 @@ license="LGPL-2.1-or-later"
 homepage="https://wiki.gnome.org/Apps/Geary"
 distfiles="${GNOME_SITE}/${pkgname}/${version%.*}/geary-${version}.tar.xz"
 checksum=75cf5fdcc534bf5bbdf223fd4b976a627ecaf16cf87a4bea51ef94fc2f38d2a8
+
+post_patch() {
+	case "$XBPS_TARGET_MACHINE" in
+		i686-musl|ppc*-musl) ;;
+		*)
+			vsed -i meson.build -e 's;@UCONTEXT_LIB@;;'
+			return 0
+			;;
+	esac
+	vsed -i meson.build -e \
+		"s;@UCONTEXT_LIB@;cc.find_library('libucontext', dirs: unwind_lib);"
+}