c99: add page

pages/common/c99.md

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+# C99
+
+> Compiles C programs according to the ISO C standard.
+
+- Compile source files and create an executable:
+
+`c99 {{file.c}}`
+
+- Compile source files and create an executable with a custom name:
+
+`c99 -o {{executable_name}} {{file.c}}`
+
+- Compile source files and create object files:
+
+`c99 -c {{file.c}}`
+
+- Compile source files, link with object files, and create an executable:
+
+`c99 {{file.c}} {{file.o}}`