Fix FTBFS on fmin redefinition

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit e199b0f778)

config.h.cmake

@@ -39,6 +39,7 @@
     #define HAS_MBSTATE 1
   #endif
 #endif
+#cmakedefine HAVE_FMIN 1
 
 // kmrml
 #cmakedefine HAVE_STDLIB_H 1

kviewshell/plugins/djvu/libdjvu/ConfigureChecks.cmake

@@ -10,6 +10,7 @@
 #################################################
 
 include( CheckFunctionExists )
+include( CheckCXXSourceCompiles )
 
 check_type_size( wchar_t WCHAR_T )
 
@@ -23,3 +24,14 @@ if( HAVE_WCHAR_T )
     check_function_exists( wcrtomb HAVE_WCRTOMB )
   endif( )
 endif( )
+
+check_cxx_source_compiles(
+  "
+   #include <cmath>
+   int main(int, char*[]) {
+     float res = fmin(0, 1);
+     return 0;
+   }
+  "
+  HAVE_FMIN
+)

kviewshell/plugins/djvu/libdjvu/DjVuPalette.cpp

@@ -97,10 +97,11 @@ inline unsigned char
 umin(unsigned char a, unsigned char b) 
 { return (a>b) ? b : a; }
 
+#if !defined(HAVE_FMIN)
 inline float 
 fmin(float a, float b) 
 { return (a>b) ? b : a; }
-
+#endif
 
 
 // ------- DJVUPALETTE