Fix building with C++14, which errors out due -Wnarrowing conversions.
See also: https://bugs.gentoo.org/show_bug.cgi?id=594680

--- a/include/lcm_ssecomplex.h
+++ b/include/lcm_ssecomplex.h
@@ -151,7 +151,7 @@
 {
   static const union {
     int i[4]; ssecomplex_t v;
-  } signbithigh = {{0,0,0,0x80000000}};
+  } signbithigh = {{0,0,0,(int)0x80000000}};
   ssecomplex_t b_im = _mm_shuffle_pd(b,b,3); // Imag. part of b in both
   const ssecomplex_t b_re = _mm_shuffle_pd(b,b,0); // Real part of b in both
   const ssecomplex_t tmp=_mm_mul_pd(a,b_re);
@@ -166,7 +166,7 @@
   ssecomplex_t b_re = _mm_set1_pd(b);
   static const union {
     int i[4]; ssecomplex_t v;
-  } signbithigh = {{0,0,0,0x80000000}};
+  } signbithigh = {{0,0,0,(int)0x80000000}};
   b_re = _mm_xor_pd(b_re, signbithigh.v); // Change sign of high
   return complex(_mm_mul_pd(a.z_, b_re));
 }
@@ -184,14 +184,14 @@
 inline complex operator- (const complex& a) {
   static const union { // (signbit,signbit)
     int i[4]; ssecomplex_t v;
-  } signbits = {{0,0x80000000,0,0x80000000}};
+  } signbits = {{0,(int)0x80000000,0,(int)0x80000000}};
   return complex(_mm_xor_pd(a, signbits.v)); // Change sign of both elements
 }
 
 inline complex conj(const complex& a) {
   static const union { // (signbit,signbit)
     int i[4]; ssecomplex_t v;
-  } signbithigh = {{0,0,0,0x80000000}};
+  } signbithigh = {{0,0,0,(int)0x80000000}};
   return complex(_mm_xor_pd(a.z_, signbithigh.v)); // Change sign of imag. part
 }