Description:
------------
Description:

When installing the GD extension using the bundled libgd, if any of the libraries used by libgd (e.g. libjpeg), are installed in a path that also happen to have a libgd installation, the extension code will include the external libgd files instead of the local ones.

Example:

1. Assume that `libjpeg` is installed at `/usr/local/include`;
2. Assume that `libgd` is also installed at `/usr/local/include`;
3. The build system will add `/usr/local/include` to CFLAGS (through pkg-config) for `libjpeg`;
3. Once you run `make`, you may end up in an error referring to `/usr/local/include/gd.h` instead of the bundled `gd.h`.

Root cause:

The bundled libgd fork includes `gd.h` and other gd-specific header files using `#include <foo.h>` rather than `#include "foo.h"`, which instructs the preprocessor to look for `foo.h` in the standard system directories and, if the file wasn't found, fall back to search in additional directories added to the search path.
Reference: https://gcc.gnu.org/onlinedocs/cpp/Search-Path.html

Solution:

Replace `#include <foo.h>` with `#include "foo.h"`, to ensure that the lookup will be executed in the local path first and then in the search path as fall back if the file was not found.

Actual result:
--------------
/Users/flavio/Documents/open-source/php-src/ext/gd/gd.c:571:48: error: implicit declaration of function 'gdPngGetVersionString' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        php_info_print_table_row(2, "libPNG Version", gdPngGetVersionString());
                                                      ^
/Users/flavio/Documents/open-source/php-src/ext/gd/gd.c:571:48: note: did you mean 'gdVersionString'?
/usr/local/include/gd.h:1687:27: note: 'gdVersionString' declared here
BGD_DECLARE(const char *) gdVersionString(void);