git: 4ba3797c9993 - main - graphics/png: fix build with clang 15

The branch main has been updated by dim (src committer):

URL: https://cgit.FreeBSD.org/ports/commit/?id=4ba3797c9993a25a082ed767d4f44234b1f7dc04

commit 4ba3797c9993a25a082ed767d4f44234b1f7dc04
Author:     Dimitry Andric <dim@FreeBSD.org>
AuthorDate: 2022-07-30 16:37:48 +0000
Commit:     Dimitry Andric <dim@FreeBSD.org>
CommitDate: 2022-07-31 17:12:11 +0000

    graphics/png: fix build with clang 15
    
    Building png with clang 15 results in an error:
    
        contrib/libtests/pngvalid.c:11662:4: error: call to undeclared function 'feenableexcept'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
           feenableexcept(FE_DIVBYZERO | FE_INVALID | FE_OVERFLOW);
           ^
    
    This is because clang 15 introduced this new warning, and fenv.h only
    declares feenableexcept() when compiling for C standards before C11.
    
    The least disruptive way to solve this is to make the port build with
    USE_CSTD=gnu89.
    
    PR:             265521
    Approved by:    portmgr (antoine)
    MFH:            2022Q3
---
 graphics/png/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/graphics/png/Makefile b/graphics/png/Makefile
index 18f0accd5f9f..d157f7187248 100644
--- a/graphics/png/Makefile
+++ b/graphics/png/Makefile
@@ -16,6 +16,7 @@ LICENSE_NAME=	libpng License
 LICENSE_FILE=	${WRKSRC}/LICENSE
 LICENSE_PERMS=	dist-mirror dist-sell pkg-mirror pkg-sell auto-accept
 
+USE_CSTD=	gnu89
 USES=		cpe libtool tar:xz
 CPE_PRODUCT=	libpng
 GNU_CONFIGURE=	yes