Update libsrk31c++ - install headers to include/srk31

libsrk31cxx/PKGBUILD

@@ -9,12 +9,17 @@ pkgdesc="libsrk31cxx-git by Stephen R. Kell"
 arch=('x86_64')
 url="https://github.com/stephenrkell/libsrk31cxx"
 license=('?')
-depends=()
+depends=(libcxxfileno)
 makedepends=('git' 'make' 'autoconf')
 install=
 source=("git+https://github.com/stephenrkell/libsrk31cxx")
 md5sums=('SKIP')
 
+prepare() {
+    cd "$srcdir/${_pkgname}"
+    sed -i '1ipkgincludedir=$(includedir)' include/Makefile.am
+}
+
 pkgver() {
     cd "$srcdir/${_pkgname}"
     printf "r%s.%s" "$(git rev-list --count HEAD)" "$(git rev-parse --short HEAD)"