contrib/libosmocore.spec: centos7: disable uring

liburing is not available in CentOS 7, so disable it there. I've
verified that this works as expected in our OBS with CentOS 7, 8 and
openSUSE Tumbleweed.

Related: OS#5751
Change-Id: Ie2399754952d460499c9355706be37f792988bac
diff --git a/contrib/libosmocore.spec.in b/contrib/libosmocore.spec.in
index 3fde143..ebd1938 100644
--- a/contrib/libosmocore.spec.in
+++ b/contrib/libosmocore.spec.in
@@ -32,7 +32,9 @@
 BuildRequires:  pkgconfig(talloc) >= 2.1.0
 BuildRequires:  pkgconfig(libmnl)
 BuildRequires:  pkgconfig(libsystemd)
+%if 0%{?centos_ver} != 7
 BuildRequires:  pkgconfig(liburing)
+%endif
 
 %description
 libosmocore is a package with various utility functions that were
@@ -339,8 +341,18 @@
 %build
 echo "%version" >.tarball-version
 autoreconf -fiv
-%configure --enable-shared --disable-static --enable-systemd-logging \
+
+CONFIGURE_FLAGS="
+	--enable-shared \
+	--disable-static \
+	--enable-systemd-logging \
 	--includedir="%_includedir/%name"
+"
+%if 0%{?centos_ver} == 7
+	CONFIGURE_FLAGS="$CONFIGURE_FLAGS --disable-uring"
+%endif
+
+%configure $CONFIGURE_FLAGS
 make %{?_smp_mflags} V=1
 
 %install