tesseract: unbreak build on modern toolchains

[ci skip]

srcpkgs/tesseract/patches/gamma.patch

@@ -0,0 +1,40 @@
+This is backported from upstream as redefining the name like that breaks
+compilation on various modern toolchains. Remove if/when a new release is made.
+--- src/engine/main.cpp
++++ src/engine/main.cpp
+@@ -508,10 +508,10 @@ static void setgamma(int val)
+ }
+ 
+ static int curgamma = 100;
+-VARFP(gamma, 30, 100, 300,
++VARFNP(gamma, reqgamma, 30, 100, 300,
+ {
+-    if(initing || gamma == curgamma) return;
+-    curgamma = gamma;
++    if(initing || reqgamma == curgamma) return;
++    curgamma = reqgamma;
+     setgamma(curgamma);
+ });
+ 
+--- src/shared/cube.h
++++ src/shared/cube.h
+@@ -3,19 +3,11 @@
+ 
+ #define _FILE_OFFSET_BITS 64
+ 
+-#ifdef __GNUC__
+-#define gamma __gamma
+-#endif
+-
+ #ifdef WIN32
+ #define _USE_MATH_DEFINES
+ #endif
+ #include <math.h>
+ 
+-#ifdef __GNUC__
+-#undef gamma
+-#endif
+-
+ #include <string.h>
+ #include <stdio.h>
+ #include <stdlib.h>