[PATCH v3] m4: dpdk: fix DPDK_LIBS generation with pkgconf >= 1.9.4

[janzizazizka]

The pkgconf older then 1.9.4 was adding extra space at the end of printed configuration elements. This was changed with [1].

With pkgconf 1.9.4 onwards the generated DPDK_LIBS creates '-ldl-latomic' instaed of '-ldl,-latomic' causing that linking fails.

To fix this append ',' always if missing at the end. The change is backwards compatible and works with both old and new pkgconf.

[1] pkgconf/pkgconf@648a224

[janzizazizka]

There seems to be many checks failing :-) but I cannot see how this change could cause those. I'll try to reproduce some of them locally to see if my change introduced a regression:

 gcc -W -Wall -Werror -Wmissing-prototypes -Wmissing-declarations -Wpointer-arith -Wcast-align -Wnested-externs -Wcast-qual -Wformat-nonliteral -Wformat-security -Wundef -Wwrite-strings -Wformat-truncation=0 -Wformat-overflow=0 -std=c11 -D_GNU_SOURCE  -mcx16 -march=native  -Wno-error=cast-align  -include rte_config.h -march=corei7 -I/usr/local/include -D_GNU_SOURCE -msse4.2 -DALLOW_EXPERIMENTAL_API -g -O2 odp_api_headers.c -o odp_api_headers_shared \
	`PKG_CONFIG_PATH=/opt/odp/lib/pkgconfig:$PKG_CONFIG_PATH pkg-config --cflags --libs libodphelper` `PKG_CONFIG_PATH=/opt/odp/lib/pkgconfig:$PKG_CONFIG_PATH pkg-config --cflags --libs libodp-dpdk`
/usr/bin/ld: cannot find : No such file or directory

[janzizazizka]

OK thanks @MatiasElo for pointing out the regression. I'll need to revisit the change, my bad.

[janzizazizka]

Found the regression. Touched one place too much where training , should not be added. Also noticed difference between pkgconf and pkg-config projects.

[janzizazizka]

Thanks to @MatiasElo it was discovered that the problem was caused by accidental edit of libodp-dpdk.pc.in so this MR was fixing just a symptom of the problem.