devel/mpfr: Add MPFR as a package

- This is a place holder incase we stop building MPFR in
  GCC.

Updates #4892

bare/config/devel/mpfr-4.2.0.cfg

@@ -0,0 +1,18 @@
+#
+# MPFR 4.2.0
+#
+
+%if %{release} == %{nil}
+%define release 1
+%endif
+
+%include %{_configdir}/base.cfg
+
+%define mpfr_version 4.2.0
+%hash sha512 mpfr-%{mpfr_version}.tar.bz2 \
+        yyqTFLlONKTqSc4mGYAulCDJguVSWKS8Qj+AJ0BjJkaj1CDn/PNzsZYYOFuLK0Eqv6En6PRzBThjQkysIziTwA==
+
+#
+# The MPFR build instructions.
+#
+%include %{_configdir}/mpfr.cfg

source-builder/config/mpfr.cfg

@@ -0,0 +1,62 @@
+#
+# The GNU Multiple-precision Floating-point computations with correct Rounding (MPFR)
+#
+# This configuration file configure's, make's and install's GMP.
+#
+
+%if %{release} == %{nil}
+%define release 1
+%endif
+
+Name:      mpfr-%{mpfr_version}-%{_host}-%{release}
+Summary:   The GNU Multiple-precision Floating-point computations with correct Rounding Library (MPFR)
+           v%{mpfr_version} for target %{_target} on host %{_host}
+Version:   %{mpfr_version}
+Release:   %{release}
+URL: 	   https://www.mpfr.org/
+
+#
+# Source
+#
+%source set mpfr https://www.mpfr.org/mpfr-%{mpfr_version}/mpfr-%{mpfr_version}.tar.bz2
+
+#
+# Prepare the source code.
+#
+%prep
+  build_top=$(pwd)
+
+  %source setup mpfr -q -n mpfr-%{mpfr_version}
+  %patch setup mpfr -p1
+
+  cd ${build_top}
+
+%build
+  build_top=$(pwd)
+
+  cd mpfr-%{mpfr_version}
+
+  %{host_build_flags}
+
+  ./configure \
+    --build=%{_build} --host=%{_host} \
+    --verbose \
+    --prefix=%{_prefix} --bindir=%{_bindir} \
+    --exec-prefix=%{_exec_prefix} \
+    --includedir=%{_includedir} --libdir=%{_libdir} \
+    --mandir=%{_mandir} --infodir=%{_infodir} \
+    --disable-shared
+
+  %{__make} %{?_smp_mflags} all
+
+  cd ${build_top}
+
+%install
+  build_top=$(pwd)
+
+  rm -rf $SB_BUILD_ROOT
+
+  cd mpfr-%{mpfr_version}
+  %{__make} DESTDIR=$SB_BUILD_ROOT install
+
+  cd ${build_top}