Link against gmp,mpfr & enable PGO,LTO for up to 1.25x speedup

PGO workload is taken from [here](https://github.com/Tensibai/benchmark-awk-vs)

**Benchmarking**

Use a different benchmark for testing to ensure we aren't just optimizing for one workload.

1. Generate some data
`yes 'SomeSampleText SomeOtherText 33 1970 YetAnotherText 777 abc 1 AndSomeMore' | head -12000000 > gawkdata.txt`

2. Benchmark
`perf stat -r 5 gawk 'BEGIN {a = 0;} /YetAnotherText/ {a ++;} END {print "a: " a;}' gawkdata.txt`

Before: 2.12259 +- 0.00260 seconds time elapsed  ( +-  0.12% )

After : 1.59791 +- 0.00152 seconds time elapsed  ( +-  0.10% )

gawk/stone.yml

@@ -9,6 +9,8 @@ description : |
 upstreams   :
     - https://ftp.gnu.org/gnu/gawk/gawk-5.1.1.tar.xz: d87629386e894bbea11a5e00515fc909dc9b7249529dad9e6a3a2c77085f7ea2
 builddeps   :
+    - pkgconfig(gmp)
+    - pkgconfig(mpfr)
     - make
     - clang
     - lld
@@ -25,3 +27,9 @@ install     : |
     %install_file %(installroot)/etc/profile.d/* -t %(installroot)/%(vendordir)/profile.d/
     rm %(installroot)/etc/profile.d/*
     rmdir %(installroot)/etc/profile.d %(installroot)/etc
+workload    : |
+    ./gawk 'BEGIN{for (i=1;i<=10000000;i++) print (i % 5?"miss":"hit"),i,"  third\t \tfourth"}' > file
+    echo "/hit [[:digit:]]*0 / { print \$4, \$1, \$3 }" > test.awk
+    ./gawk -f test.awk file | ./gawk '!seen[$0]++{unq++;r=$0} END{print ((unq==1) && (seen[r]==1000000) && (r=="fourth hit third")) ? "PASS" : "FAIL"}'
+tuning      :
+    - lto