libplacebo: fix glslang build failure

Closes: https://trac.macports.org/ticket/73919

devel/libplacebo/Portfile

@@ -49,9 +49,17 @@ configure.args-append   -Dvulkan=disabled \
                         -Ddemos=false \
                         -Dtests=false \
                         -Dglslang=disabled \
+                        -Dshaderc=disabled \
                         -Dxxhash=enabled \
                         -Dlcms=enabled \
                         -Dunwind=disabled
+# consider adding libdovi later: https://github.com/quietvoid/dovi_tool
+
+# https://trac.macports.org/ticket/73919, https://cgit.freebsd.org/ports/commit/?id=3e04376300805a264a0533d3557e6c7bb2855600
+post-patch {
+    reinplace "/find.*glslang.*static/s|)|, dirs: vulkan_lib_dirs)|" ${worksrcpath}/src/glsl/meson.build
+}
+configure.args-append   -Dvulkan-sdk=${prefix}
 
 compiler.c_standard     2011
 compiler.cxx_standard   2020
@@ -90,7 +98,7 @@ variant demo description {build demo programs} {
                         -Ddemos=true
 }
 
-variant glslang description {enable glslang SPIR-V compiler} {
+variant glslang description {enable glslang SPIR-V compiler support} {
     depends_lib-append  port:glslang
     configure.args-replace \
                         -Dglslang=disabled \