e2fsprogs: fix glibc compile issue (FS#1749,FS#1796)

Fixes the following build error:

.../toolchain-i386_pentium4_gcc-7.3.0_glibc/lib/gcc/i486-openwrt-linux-gnu/7.3.0/../../../../i486-openwrt-linux-gnu/bin/ld: ../lib/libcom_err.so: undefined reference to `sem_post’
.../toolchain-i386_pentium4_gcc-7.3.0_glibc/lib/gcc/i486-openwrt-linux-gnu/7.3.0/../../../../i486-openwrt-linux-gnu/bin/ld: ../lib/libcom_err.so: undefined reference to `sem_wait'
.../toolchain-i386_pentium4_gcc-7.3.0_glibc/lib/gcc/i486-openwrt-linux-gnu/7.3.0/../../../../i486-openwrt-linux-gnu/bin/ld: ../lib/libcom_err.so: undefined reference to `sem_init’
.../toolchain-i386_pentium4_gcc-7.3.0_glibc/lib/gcc/i486-openwrt-linux-gnu/7.3.0/../../../../i486-openwrt-linux-gnu/bin/ld: ../lib/libcom_err.so: undefined reference to `sem_destroy’

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

package/utils/e2fsprogs/Makefile

@@ -132,6 +132,8 @@ $(call Package/e2fsprogs)
 endef
 
 TARGET_CFLAGS += $(FPIC) -ffunction-sections -fdata-sections -flto
+
+TARGET_LDFLAGS += $(if $(CONFIG_USE_GLIBC),-lrt)
 TARGET_LDFLAGS += -flto
 
 CONFIGURE_ARGS += \