Moved #include "cpuid.h" to bli_cpuid.c.

Details:
- Relocated the #include "cpuid.h" directive from bli_cpuid.h to
  bli_cpuid.c. This was done because cpuid.h (which is pulled into
  the post-build blis.h developer header) doesn't protect its
  definitions with a preprocessor guard of the form:

    #ifndef FOOBAR_H
    #define FOOBAR_H
    // header contents.
    #endif

  and as a result, applications (previously) could not #include both
  blis.h and cpuid.h (since the former was already including the
  latter). Thanks to Bhaskar Nallani for raising this issue via #393
  and to Devin Matthews for suggesting this fix.
- CREDITS file update.

CREDITS

@@ -56,6 +56,7 @@ but many others have contributed code and feedback, including
   Simon Lukas Märtens      @ACSimon33          (RWTH Aachen University)
   Devin Matthews           @devinamatthews     (The University of Texas at Austin)
   Stefanos Mavros          @smavros
+  Bhaskar Nallani          @BhaskarNallani     (AMD)
   Nisanth Padinharepatt                        (AMD)
   Ajay Panyala             @ajaypanyala
   Devangi Parikh           @dnparikh           (The University of Texas at Austin)

frame/base/bli_cpuid.c

@@ -46,20 +46,22 @@
   #define __arm__
 #endif
 
-#ifndef BLIS_CONFIGURETIME_CPUID
-  #include "blis.h"
-#else
+#ifdef BLIS_CONFIGURETIME_CPUID
   #define BLIS_EXPORT_BLIS
   #include "bli_system.h"
   #include "bli_type_defs.h"
   #include "bli_cpuid.h"
   #include "bli_arch.h"
+#else
+  #include "blis.h"
 #endif
 
 // -----------------------------------------------------------------------------
 
 #if defined(__x86_64__) || defined(_M_X64) || defined(__i386) || defined(_M_IX86)
 
+#include "cpuid.h"
+
 arch_t bli_cpuid_query_id( void )
 {
 	uint32_t vendor, family, model, features;

frame/base/bli_cpuid.h

@@ -125,7 +125,9 @@ static bool_t bli_cpuid_has_features( uint32_t have, uint32_t want )
 
 #if defined(__x86_64__) || defined(_M_X64) || defined(__i386) || defined(_M_IX86)
 
-#include "cpuid.h"
+// cpuid.h is now #included in bli_cpuid.c instead of here. See issue #393
+// for more information why this move was made.
+//#include "cpuid.h"
 
 void get_cpu_name( char *cpu_name );
 int  vpu_count( void );