[frogr] Search for gcrypt using pkg-config if a .pc file is available

[Mario Sanchez Prada <msanchez src gnome org>]

commit 5975d51aead1e8e47e3740e11827f4b062eab552
Author: Mario Sanchez Prada <msanchez gnome org>
Date:   Fri Mar 17 17:55:10 2017 +0000

    Search for gcrypt using pkg-config if a .pc file is available

 configure.ac |   16 ++++++++++++++++
 1 files changed, 16 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 70134d0..45e3292 100644
--- a/configure.ac
+++ b/configure.ac
@@ -45,6 +45,22 @@ FROGR_CFLAGS="$FROGR_CFLAGS $JSON_GLIB_CFLAGS"
 FROGR_LIBS="$FROGR_LIBS $JSON_GLIB_LIBS"
 
 LIBGCRYPT_MIN_VERSION=1.5.0
+PKG_CHECK_MODULES(LIBGCRYPT, libgcrypt >= $LIBGCRYPT_MIN_VERSION,
+                             [found_gcrypt="yes"], [found_gcrypt="no"])
+
+# libgcrypt might not have a .pc file installed
+if test "x$found_crypt" = "xno"; then
+   AM_PATH_LIBGCRYPT($LIBGCRYPT_MIN_VERSION, HAVE_GCRYPT=yes, HAVE_GCRYPT=no)
+   if test "x$HAVE_GCRYPT" = "xno"; then
+      AC_MSG_ERROR([libgcrypt not found, please install it])
+   fi
+fi
+
+AC_DEFINE_UNQUOTED([LIBGCRYPT_MIN_VERSION], ["$LIBGCRYPT_MIN_VERSION"], [Minimum supported gcrypt version])
+FROGR_CFLAGS="$FROGR_CFLAGS $LIBGCRYPT_CFLAGS"
+FROGR_LIBS="$FROGR_LIBS $LIBGCRYPT_LIBS"
+
+
 # libgcrypt does not provide a .pc file
 AM_PATH_LIBGCRYPT($LIBGCRYPT_MIN_VERSION, HAVE_GCRYPT=yes, HAVE_GCRYPT=no)
 if test "x$HAVE_GCRYPT" = "xno"; then