Use make macros

https://docs.fedoraproject.org/en-US/packaging-guidelines/#_parallel_make

optipng.spec

@@ -29,19 +29,20 @@ rm -rf src/libpng src/zlib
 
 
 %build
+%set_build_flags
 ./configure -prefix=%{_prefix} -mandir=%{_mandir} \
     -with-system-zlib -with-system-libpng
-make %{?_smp_mflags} CFLAGS="$RPM_OPT_FLAGS" LDFLAGS="$RPM_LD_FLAGS"
+%make_build
 
 
 %install
 rm -rf $RPM_BUILD_ROOT
-make install DESTDIR=$RPM_BUILD_ROOT
+%make_install
 chmod -c 755 $RPM_BUILD_ROOT%{_bindir}/optipng
 
 
 %check
-make test CFLAGS="$RPM_OPT_FLAGS" LDFLAGS="$RPM_LD_FLAGS"
+%__make test
 
 
 %files