Fixes for build issues with upstream imgui

Author: azonenberg

imstb_truetype.h

@@ -4022,7 +4022,7 @@ STBTT_DEF void stbtt_PackSetSkipMissingCodepoints(stbtt_pack_context *spc, int s
 
 #define STBTT__OVER_MASK  (STBTT_MAX_OVERSAMPLE-1)
 
-static void stbtt__h_prefilter(unsigned char *pixels, int w, int h, int stride_in_bytes, unsigned int kernel_width)
+void stbtt__h_prefilter(unsigned char *pixels, int w, int h, int stride_in_bytes, unsigned int kernel_width)
 {
    unsigned char buffer[STBTT_MAX_OVERSAMPLE];
    int safe_w = w - kernel_width;
@@ -4084,7 +4084,7 @@ static void stbtt__h_prefilter(unsigned char *pixels, int w, int h, int stride_i
    }
 }
 
-static void stbtt__v_prefilter(unsigned char *pixels, int w, int h, int stride_in_bytes, unsigned int kernel_width)
+void stbtt__v_prefilter(unsigned char *pixels, int w, int h, int stride_in_bytes, unsigned int kernel_width)
 {
    unsigned char buffer[STBTT_MAX_OVERSAMPLE];
    int safe_h = h - kernel_width;
@@ -4146,7 +4146,7 @@ static void stbtt__v_prefilter(unsigned char *pixels, int w, int h, int stride_i
    }
 }
 
-static float stbtt__oversample_shift(int oversample)
+float stbtt__oversample_shift(int oversample)
 {
    if (!oversample)
       return 0.0f;