Fix names of Gentoo packages

Gentoo renamed some build tools in late 2023. We update the names here
to fix the broken CI runs for Gentoo (that happen e.g. for cypari2.)

Author: saraedum

build/pkgs/_bootstrap/distros/gentoo.txt

@@ -1,3 +1,3 @@
-sys-devel/autoconf
-sys-devel/automake
-sys-devel/libtool
+dev-build/autoconf
+dev-build/automake
+dev-build/libtool

build/pkgs/_prereq/distros/gentoo.txt

@@ -1,6 +1,6 @@
 sys-devel/binutils
 sys-libs/binutils-libs
-sys-devel/make
+dev-build/make
 dev-scheme/guile
 dev-libs/libffi
 app-arch/tar