Update default flags variables

Add note about {F,FF,OBJ}FLAGS variables.
Address #162

Signed-off-by: Shane Peelar <lookatyouhacker@gmail.com>

README.md

@@ -42,6 +42,7 @@ CXXFLAGS="${CFLAGS}"
 LDFLAGS="${LDFLAGS} -Wl,--hash-style=gnu"
 
 #Obtained from app-portage/cpuid2cpuflags utility
+#Highly recommended to add these
 CPU_FLAGS_X86="aes avx avx2 f16c fma3 mmx mmxext pclmul popcnt sse sse2 sse3 sse4_1 sse4_2 ssse3"
 ...
 ~~~
@@ -72,11 +73,22 @@ LDFLAGS="${LDFLAGS} -Wl,--hash-style=gnu"
 ...
 ~~~
 
+
 For more details, there are extensive comments in both files.
 Regardless of which approach you choose, you should ensure that `CXXFLAGS` is set to `CFLAGS`,
 and your Portage profile's `LDFLAGS` are respected.  I also enable `-Wl,--hash-style=gnu` as it
 can help catch packages that don't respect `LDFLAGS`, but this is optional.
 
+Additionally, you may want to set environment variables for other languages compiled by GCC as well, for
+cross-language LTO:
+
+~~~
+FCFLAGS="${CFLAGS}"
+FFLAGS="${CFLAGS}"
+OBJCFLAGS="${CFLAGS}"
+OBJCXXFLAGS="${CFLAGS}"
+~~~
+
 It is strongly recommended to use the latest GCC (8.2.0 at the time of writing), latest binutils (2.31.1 currently), and latest glibc (2.28 currently).
 
 When you find a problem, whether it's a package not playing nice with -O3, Graphite, or LTO, consider opening an issue here or sending a pull request with the overrides needed to get the package working.  Over time, we should be able to achieve full coverage of `/usr/portage` this way and provide a one size fits all solution, and not to mention help improve some open source software through the bug reports that will no doubt be generated! 

sys-config/ltoize/files/make.conf.lto

@@ -23,6 +23,16 @@
 
 #CXXFLAGS="${CFLAGS}"
 
+#In addition, you may want to modify the environment variables for other languages compiled with GCC as well:
+
+#FCFLAGS="${CFLAGS}"
+#FFLAGS="${CFLAGS}"
+#OBJCFLAGS="${CFLAGS}"
+#OBJCXXFLAGS="${CFLAGS}"
+
+#This list is pulled from the autotools documentation:
+#https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Environment-Variable-Index.html
+
 #Your LDFLAGS should contain *ALL* of your CFLAGS for LTO to work.  It must receieve all optimization options, march, etc.
 #package.cflags takes care of this for you--no need to manually add your {C,CXX}FLAGS here.
 #It's usually a good idea to enable -Wl,--hash-style=gnu as well to help find packages which don't respect LDFLAGS

sys-config/ltoize/files/make.conf.lto.defines

@@ -14,8 +14,9 @@
 #* If you want -fipa-pta, include "${IPA}" in your CFLAGS
 #* Anything else is up to you, such as -march, -pipe, -O{3,2,s,1}, etc...
 #* CXXFLAGS should be set to CFLAGS
+#* Optionally, set other *FLAGS for languages compiled with GCC as well (See make.conf.lto)
 #* LDFLAGS of your Gentoo profile should be respected.  Consider adding -Wl,--hash-style=gnu.
-#  See make.conf.lto for details.
+#  See make.conf.lto for more details.
 
 #FLTO is of the form -flto[=n] where n is the number of threads to use during linking.
 #It's usually a good idea to set this to the number of hardware threads in your system