Fix caddr_t error on icc

[dtrudg]

On an RHEL6.8 environment where the Intel 2015 icc compiler is used to build R, installation of the Cairo R package fails as the caddr_t type is not defined.

The Xlib docs specify that the calls using caddr_t temp actually take an XPointer. Replacing caddr_t with XPointer fixes compilation with the intel compiler.

caddr_t is a kernel typedef - believe that XPointer should be preferred here.

[gifi]

Same issue with

$ cat /usr/lib/os-release
NAME=Fedora
VERSION="24 (Workstation Edition)"
ID=fedora
VERSION_ID=24
PRETTY_NAME="Fedora 24 (Workstation Edition)"
ANSI_COLOR="0;34"
CPE_NAME="cpe:/o:fedoraproject:fedora:24"
HOME_URL="https://fedoraproject.org/"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Fedora"
REDHAT_BUGZILLA_PRODUCT_VERSION=24
REDHAT_SUPPORT_PRODUCT="Fedora"
REDHAT_SUPPORT_PRODUCT_VERSION=24
PRIVACY_POLICY_URL=https://fedoraproject.org/wiki/Legal:PrivacyPolicy
VARIANT="Workstation Edition"
VARIANT_ID=workstation

$ gcc --version
gcc (GCC) 6.2.1 20160916 (Red Hat 6.2.1-2)

> sessionInfo()
R Under development (unstable) (2016-11-25 r71694)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Fedora 24 (Workstation Edition)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_GB.UTF-8        LC_COLLATE=en_US.UTF-8
 [5] LC_MONETARY=en_GB.UTF-8    LC_MESSAGES=en_US.UTF-8    LC_PAPER=en_GB.UTF-8       LC_NAME=C
 [9] LC_ADDRESS=C               LC_TELEPHONE=C             LC_MEASUREMENT=en_GB.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] compiler_3.4.0 tools_3.4.0

> install.packages("Cairo_1.5-9.tar.gz", repos = NULL)
# Or alternatively, with
#> install.packages("Cairo",,"http://rforge.net/",type="source")

…
xlib-backend.c: In function ‘Rcairo_new_xlib_backend’:
xlib-backend.c:366:57: error: ‘caddr_t’ undeclared (first use in this function)
   XSaveContext(xd->display, xd->window, devPtrContext, (caddr_t) xd);
                                                         ^~~~~~~
xlib-backend.c:366:57: note: each undeclared identifier is reported only once for each function it appears in
xlib-backend.c:366:66: error: expected ‘)’ before ‘xd’
   XSaveContext(xd->display, xd->window, devPtrContext, (caddr_t) xd);

This PR fixes the issue:

$ git clone --recursive https://github.com/s-u/Cairo.git Cairo
# Edit src/xlib-backend.c accordingly to the PR.
$ grep -n 'caddr_t' src/xlib-backend.c
95:	XPointer temp; /* caddr_t temp; */
182:	XPointer temp; /* caddr_t temp; */
366:		XSaveContext(xd->display, xd->window, devPtrContext, (XPointer) xd); /* XSaveContext(xd->display, xd->window, devPtrContext, (caddr_t) xd); */

$ ./mkdist
$ cd ..
$ R CMD INSTALL Cairo_1.5-9.tar.gz
…
** testing if installed package can be loaded
* DONE (Cairo)

[gifi]

Actually, the issue is reproducible only with C 11, that is CFLAGS += -std=c11 or any other compatible flag.

[s-u]

Thanks!