Fix Linux backward compat issues w/ leptonica

Never pull the GLIBC_2.22 version of fmemopen on Linux.
None of our ARM targets run anything that new.
Fix koreader#421

Note to mainteners: there's an updated patch for the upcoming leptonica
version, because the code got easier to deal with ;).

thirdparty/leptonica/CMakeLists.txt

@@ -18,6 +18,9 @@ include(ExternalProject)
 ExternalProject_Add(
     ${PROJECT_NAME}
     DOWNLOAD_COMMAND ${CMAKE_COMMAND} -P ${GIT_CLONE_SCRIPT_FILENAME}
+    # Make sure we use the old fmemopen symbol on Linux when building against glibc >= 2.22 (c.f. base#421)
+    # NOTE: The patch will be much simpler w/ the upcoming leptonica version, there's a 1.74 version of the patch already in our tree for when that time comes ;)
+    PATCH_COMMAND patch -N -p1 < ${CMAKE_CURRENT_SOURCE_DIR}/leptonica-1.72-fmemopen-compat-symbol.patch
     CONFIGURE_COMMAND ""
     # skip build and install, libk2pdfopt will build it
     BUILD_COMMAND ""

thirdparty/leptonica/leptonica-1.72-fmemopen-compat-symbol.patch

@@ -0,0 +1,60 @@
+diff --git a/src/bmpio.c b/src/bmpio.c
+index e775dd2..68dc56c 100644
+--- a/src/bmpio.c
++++ b/src/bmpio.c
+@@ -554,6 +554,7 @@ RGBA_QUAD  *pquad;
+ #endif  /* HAVE_CONFIG_H */
+
+ #if HAVE_FMEMOPEN
++__asm__(".symver fmemopen,fmemopen@GLIBC_2.2.5");
+ extern FILE *open_memstream(char **data, size_t *size);
+ extern FILE *fmemopen(void *data, size_t size, const char *mode);
+ #endif  /* HAVE_FMEMOPEN */
+diff --git a/src/jp2kio.c b/src/jp2kio.c
+index 9eb88d1..105b160 100644
+--- a/src/jp2kio.c
++++ b/src/jp2kio.c
+@@ -743,6 +743,7 @@ opj_image_cmptparm_t  cmptparm[4];
+  *                         Read/write to memory                        *
+  *---------------------------------------------------------------------*/
+ #if HAVE_FMEMOPEN
++__asm__(".symver fmemopen,fmemopen@GLIBC_2.2.5");
+ extern FILE *open_memstream(char **data, size_t *size);
+ extern FILE *fmemopen(void *data, size_t size, const char *mode);
+ #endif  /* HAVE_FMEMOPEN */
+diff --git a/src/jpegio.c b/src/jpegio.c
+index 06185da..ddc4a3c 100644
+--- a/src/jpegio.c
++++ b/src/jpegio.c
+@@ -939,6 +939,7 @@ jmp_buf                      jmpbuf;  /* must be local to the function */
+  *                         Read/write to memory                        *
+  *---------------------------------------------------------------------*/
+ #if HAVE_FMEMOPEN
++__asm__(".symver fmemopen,fmemopen@GLIBC_2.2.5");
+ extern FILE *open_memstream(char **data, size_t *size);
+ extern FILE *fmemopen(void *data, size_t size, const char *mode);
+ #endif  /* HAVE_FMEMOPEN */
+diff --git a/src/pngio.c b/src/pngio.c
+index 19f6c55..79b7ed3 100644
+--- a/src/pngio.c
++++ b/src/pngio.c
+@@ -1252,6 +1252,7 @@ l_pngSetReadStrip16To8(l_int32  flag)
+  *                         Read/write to memory                        *
+  *---------------------------------------------------------------------*/
+ #if HAVE_FMEMOPEN
++__asm__(".symver fmemopen,fmemopen@GLIBC_2.2.5");
+ extern FILE *open_memstream(char **data, size_t *size);
+ extern FILE *fmemopen(void *data, size_t size, const char *mode);
+ #endif  /* HAVE_FMEMOPEN */
+diff --git a/src/pnmio.c b/src/pnmio.c
+index 3b4b931..00b4e47 100644
+--- a/src/pnmio.c
++++ b/src/pnmio.c
+@@ -601,6 +601,7 @@ PIX       *pixs;
+ #endif  /* HAVE_CONFIG_H */
+
+ #if HAVE_FMEMOPEN
++__asm__(".symver fmemopen,fmemopen@GLIBC_2.2.5");
+ extern FILE *open_memstream(char **data, size_t *size);
+ extern FILE *fmemopen(void *data, size_t size, const char *mode);
+ #endif  /* HAVE_FMEMOPEN */

thirdparty/leptonica/leptonica-1.74-fmemopen-compat-symbol.patch

@@ -0,0 +1,12 @@
+diff --git a/src/utils.c b/src/utils.c
+index 76e7d43..9da46b0 100644
+--- a/src/utils.c
++++ b/src/utils.c
+@@ -1912,6 +1912,7 @@ FILE  *fp;
+         return (FILE *)ERROR_PTR("data not defined", procName, NULL);
+
+ #if HAVE_FMEMOPEN
++    __asm__(".symver fmemopen,fmemopen@GLIBC_2.2.5");
+     if ((fp = fmemopen((void *)data, size, "rb")) == NULL)
+         return (FILE *)ERROR_PTR("stream not opened", procName, NULL);
+ #else  /* write to tmp file */