Add missing build-requires on GCC

Packages that are built with GCC must BuildRequire it.
See: https://fedoraproject.org/wiki/Packaging:C_and_C%2B%2B#BuildRequires_and_Requires

jna.spec

@@ -1,6 +1,6 @@
 Name:           jna
 Version:        4.3.0
-Release:        2%{?dist}
+Release:        3%{?dist}
 Summary:        Pure Java access to native libraries
 # Most of code is dual-licensed under either LGPL 2.1 only or Apache
 # License 2.0.  WeakIdentityHashMap.java was taken from Apache CXF,
@@ -26,6 +26,8 @@ Patch3:         0004-Fix-javadoc-build.patch
 # We manually require libffi because find-requires doesn't work
 # inside jars.
 Requires:       libffi
+BuildRequires:  gcc
+BuildRequires:  make
 BuildRequires:  java-devel
 BuildRequires:  jpackage-utils
 BuildRequires:  libffi-devel
@@ -132,6 +134,9 @@ cp -a doc/javadoc/* %{buildroot}%{_javadocdir}/%{name}
 
 
 %changelog
+* Wed Feb  1 2017 Mikolaj Izdebski <mizdebsk@redhat.com> - 4.3.0-3
+- Add missing build-requires on GCC
+
 * Tue Jan 31 2017 Michael Simacek <msimacek@redhat.com> - 4.3.0-2
 - Try to fix javadoc generation