[PATCH] configure: add workaround for systems without zlib.pc

[Felipe Contreras]

Some systems (e.g. FreeBSD) might not have installed the appropriate
pkg-config file as they should. We can workaround the issue by creating
the .pc file they should have distributed.

Signed-off-by: Felipe Contreras <felipe.contreras at gmail.com>
---
 compat/.gitignore    |  1 +
 compat/gen_zlib_pc.c | 18 ++++++++++++++++++
 configure            |  9 +++++++++
 3 files changed, 28 insertions(+)
 create mode 100644 compat/.gitignore
 create mode 100644 compat/gen_zlib_pc.c

diff --git a/compat/.gitignore b/compat/.gitignore
new file mode 100644
index 0000000..107ba17
--- /dev/null
+++ b/compat/.gitignore
@@ -0,0 +1 @@
+zlib.pc
diff --git a/compat/gen_zlib_pc.c b/compat/gen_zlib_pc.c
new file mode 100644
index 0000000..198a727
--- /dev/null
+++ b/compat/gen_zlib_pc.c
@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include <zlib.h>
+
+static const char *template =
+	"prefix=/usr\n"
+	"exec_prefix=${prefix}\n"
+	"libdir=${exec_prefix}/lib\n"
+	"\n"
+	"Name: zlib\n"
+	"Description: zlib compression library\n"
+	"Version: %s\n"
+	"Libs: -lz\n";
+
+int main(void)
+{
+	printf(template, ZLIB_VERSION);
+	return 0;
+}
diff --git a/configure b/configure
index 9bde2eb..35dd21f 100755
--- a/configure
+++ b/configure
@@ -340,6 +340,15 @@ else
     errors=$((errors + 1))
 fi
 
+if ! pkg-config --exists zlib; then
+  ${CC} ${zlib_cflags} -o compat/gen_zlib_pc \
+	  "$srcdir"/compat/gen_zlib_pc.c ${zlib_ldflags} > /dev/null 2>&1 &&
+  compat/gen_zlib_pc > compat/zlib.pc &&
+  PKG_CONFIG_PATH="$PKG_CONFIG_PATH":compat &&
+  export PKG_CONFIG_PATH
+  rm -f compat/gen_zlib_pc
+fi
+
 printf "Checking for zlib (>= 1.2.5.2)... "
 have_zlib=0
 if pkg-config --atleast-version=1.2.5.2 zlib; then
-- 
1.9.2+fc1~45~g3953d93