Fix installs with non-standard buildroots (#1299860)

libtommath.spec

@@ -1,6 +1,6 @@
 Name:           libtommath
 Version:        1.0
-Release:        3%{?dist}
+Release:        4%{?dist}
 Summary:        A portable number theoretic multiple-precision integer library
 License:        Public Domain
 URL:            http://www.libtom.org/
@@ -64,7 +64,7 @@ make %{?_smp_mflags} LIBPATH=%{_libdir} -f makefile.shared
 make -f makefile poster manual docs
 
 %install
-%make_install LIBPATH=%{_libdir} -f makefile.shared
+%make_install LIBPATH=%{_libdir} INCPATH=%{_includedir} -f makefile.shared
 
 find %{buildroot} -name '*.la' -delete
 find %{buildroot} -name '*.a' -delete
@@ -86,6 +86,9 @@ find %{buildroot} -name '*.a' -delete
 %doc bn.pdf poster.pdf tommath.pdf
 
 %changelog
+* Tue Feb 23 2016 Simone Caronni <negativo17@gmail.com> - 1.0-4
+- Fix installs with non-standard buildroots (#1299860).
+
 * Tue Feb 23 2016 Simone Caronni <negativo17@gmail.com> - 1.0-3
 - Remove useless latex build requirements.