gnu: ghostscript: Fix build with FreeType 2.10.4.

This fixes a build failure from 79b31767d0.

* gnu/packages/patches/ghostscript-freetype-compat.patch: New file.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
* gnu/packages/ghostscript.scm (ghostscript)[source](patches): Add it.

gnu/local.mk

@@ -1055,6 +1055,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/ghc-monad-par-fix-tests.patch		\
   %D%/packages/patches/ghc-pandoc-fix-html-tests.patch		\
   %D%/packages/patches/ghc-pandoc-fix-latex-test.patch		\
+  %D%/packages/patches/ghostscript-freetype-compat.patch	\
   %D%/packages/patches/ghostscript-no-header-id.patch		\
   %D%/packages/patches/ghostscript-no-header-uuid.patch		\
   %D%/packages/patches/ghostscript-no-header-creationdate.patch \

gnu/packages/ghostscript.scm

@@ -170,7 +170,8 @@ printing, and psresize, for adjusting page sizes.")
         (sha256
          (base32
           "0z1w42y2jmcpl2m1l3z0sfii6zmvzcwcgzn6bydklia6ig7jli2p"))
-        (patches (search-patches "ghostscript-no-header-creationdate.patch"
+        (patches (search-patches "ghostscript-freetype-compat.patch"
+                                 "ghostscript-no-header-creationdate.patch"
                                  "ghostscript-no-header-id.patch"
                                  "ghostscript-no-header-uuid.patch"))
         (modules '((guix build utils)))

gnu/packages/patches/ghostscript-freetype-compat.patch

@@ -0,0 +1,35 @@
+Fix build with FreeType 2.10.3 and newer.
+
+Taken from upstream:
+https://git.ghostscript.com/?p=ghostpdl.git;a=commitdiff;h=41ef9a0bc36b9db7115fbe9623f989bfb47bbade
+
+diff --git a/base/fapi_ft.c b/base/fapi_ft.c
+--- a/base/fapi_ft.c
++++ b/base/fapi_ft.c
+@@ -125,7 +125,7 @@ static void
+ delete_inc_int_info(gs_fapi_server * a_server,
+                     FT_IncrementalRec * a_inc_int_info);
+ 
+-FT_CALLBACK_DEF(void *)
++static void *
+ FF_alloc(FT_Memory memory, long size)
+ {
+     gs_memory_t *mem = (gs_memory_t *) memory->user;
+@@ -133,7 +133,7 @@ FF_alloc(FT_Memory memory, long size)
+     return (gs_malloc(mem, size, 1, "FF_alloc"));
+ }
+ 
+-FT_CALLBACK_DEF(void *)
++static void *
+     FF_realloc(FT_Memory memory, long cur_size, long new_size, void *block)
+ {
+     gs_memory_t *mem = (gs_memory_t *) memory->user;
+@@ -153,7 +153,7 @@ FT_CALLBACK_DEF(void *)
+     return (tmp);
+ }
+ 
+-FT_CALLBACK_DEF(void)
++static void
+     FF_free(FT_Memory memory, void *block)
+ {
+     gs_memory_t *mem = (gs_memory_t *) memory->user;